Re: rmk/for-next bisection: baseline.login on bcm2836-rpi-2-b - Russell King

From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Nicolas Pitre <nico@fluxnic.net>,
	Linus Walleij <linus.walleij@linaro.org>,
	kernelci-results@groups.io,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Olof Johansson <olof@lixom.net>, Mike Rapoport <rppt@kernel.org>,
	Marc Zyngier <maz@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Collabora Kernel ML <kernel@collabora.com>
Subject: Re: rmk/for-next bisection: baseline.login on bcm2836-rpi-2-b
Date: Fri, 13 Nov 2020 15:58:25 +0000	[thread overview]
Message-ID: <20201113155825.GD1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <ce91a878-5ce3-614d-d10c-569b891b12d0@collabora.com>

On Fri, Nov 13, 2020 at 03:43:27PM +0000, Guillaume Tucker wrote:
> On 13/11/2020 10:35, Ard Biesheuvel wrote:
> > On Fri, 13 Nov 2020 at 11:31, Guillaume Tucker
> > <guillaume.tucker@collabora.com> wrote:
> >>
> >> Hi Ard,
> >>
> >> Please see the bisection report below about a boot failure on
> >> RPi-2b.
> >>
> >> Reports aren't automatically sent to the public while we're
> >> trialing new bisection features on kernelci.org but this one
> >> looks valid.
> >>
> >> There's nothing in the serial console log, probably because it's
> >> crashing too early during boot.  I'm not sure if other platforms
> >> on kernelci.org were hit by this in the same way, but there
> >> doesn't seem to be any.
> >>
> >> The same regression can be see on rmk's for-next branch as well
> >> as in linux-next.  It happens with both bcm2835_defconfig and
> >> multi_v7_defconfig.
> >>
> >> Some more details can be found here:
> >>
> >>   https://kernelci.org/test/case/id/5fae44823818ee918adb8864/
> >>
> >> If this looks like a real issue but you don't have a platform at
> >> hand to reproduce it, please let us know if you would like the
> >> KernelCI test to be re-run with earlyprintk or some debug config
> >> turned on, or if you have a fix to try.
> >>
> >> Best wishes,
> >> Guillaume
> >>
> > 
> > Hello Guillaume,
> > 
> > That patch did have an issue, but it was already fixed by
> > 
> > https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9020/1
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=fc2933c133744305236793025b00c2f7d258b687
> > 
> > Could you please double check whether cherry-picking that on top of
> > the first bad commit fixes the problem?
> 
> Sadly this doesn't appear to be fixing the issue.  I've
> cherry-picked your patch on top of the commit found by the
> bisection but it still didn't boot, here's the git log
> 
> cbb9656e83ca ARM: 9020/1: mm: use correct section size macro to describe the FDT virtual address
> 7a1be318f579 ARM: 9012/1: move device tree mapping out of linear region
> e9a2f8b599d0 ARM: 9011/1: centralize phys-to-virt conversion of DT/ATAGS address
> 3650b228f83a Linux 5.10-rc1
> 
> Test log: https://people.collabora.com/~gtucker/lava/boot/rpi-2-b/v5.10-rc1-3-gcbb9656e83ca/
> 
> There's no output so it's hard to tell what is going on, but
> reverting the bad commmit does make the board to boot (that's
> what "revert: PASS" means in the bisect report).  So it's
> unlikely that there is another issue causing the boot failure.

These silent boot failures are precisely what the DEBUG_LL stuff (and
early_printk) is supposed to help with - getting the kernel messages
out when there is an oops before the serial console is initialised.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!