linux-kernel - Re: [BUG][BISECTED] Freeze at loading init ramdisk

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Date: Thu, 18 Jan 2024 21:04:05 +0100
From: Mirsad Todorovac <mirsad.todorovac@....unizg.hr>
To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 Helge Deller <deller@....de>,
 "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
 Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Hans de Goede <hdegoede@...hat.com>, Huacai Chen <chenhuacai@...nel.org>,
 Javier Martinez Canillas <javierm@...hat.com>,
 Linus Walleij <linus.walleij@...aro.org>,
 Prathu Baronia <prathubaronia2011@...il.com>, Sam Ravnborg
 <sam@...nborg.org>, Sui Jingfeng <suijingfeng@...ngson.cn>,
 Thomas Zimmermann <tzimmermann@...e.de>, dri-devel@...ts.freedesktop.org,
 linux-fbdev@...r.kernel.org, linux-parisc@...r.kernel.org
Subject: Re: [BUG][BISECTED] Freeze at loading init ramdisk



On 1/18/24 08:45, Uwe Kleine-König wrote:
> Hello Mirsad,
> 
> On Wed, Jan 17, 2024 at 07:47:49PM +0100, Mirsad Todorovac wrote:
>> On 1/16/24 01:32, Mirsad Todorovac wrote:
>>> On the Ubuntu 22.04 LTS Jammy platform, on a mainline vanilla torvalds tree kernel, the boot
>>> freezes upon first two lines and before any systemd messages.
>>>
>>> (Please find the config attached.)
>>>
>>> Bisecting the bug led to this result:
>>>
>>> marvin@...iant:~/linux/kernel/linux_torvalds$ git bisect good
>>> d97a78423c33f68ca6543de510a409167baed6f5 is the first bad commit
>>> commit d97a78423c33f68ca6543de510a409167baed6f5
>>> Merge: 61da593f4458 689237ab37c5
>>> Author: Linus Torvalds <torvalds@...ux-foundation.org>
>>> Date:   Fri Jan 12 14:38:08 2024 -0800
>>>
>>> [...]
>>>
>>> Hope this helps.
>>
>> P.S.
>>
>> As I see that this is a larger merge commit, with 5K+ lines changed, I don't think I can
>> bisect further to determine the culprit.
> 
> Actually it's not that hard. If a merge commit is the first bad commit
> for a bisection, either the merge wasn't done correctly (less likely,
> looking at d97a78423c33f68ca6543de510a409167baed6f5 I'd bet this isn't
> the problem); or changes on different sides conflict or you did
> something wrong during bisection.
> 
> To rule out the third option, you can just retest d97a78423c33,
> 61da593f4458 and 689237ab37c5. If d97a78423c33 is the only bad one, you
> did it right.

This was confirmed.

> Then to further debug the second option you can find out the offending
> commit on each side with a bisection as follows, here for the RHS (i.e.
> 689237ab37c5):
> 
> 	git bisect start 689237ab37c5 $(git merge-base 61da593f4458 689237ab37c5)
> 
> and then in each bisection step do:
> 
> 	git merge --no-commit 61da593f4458
> 	test if the problem is present
> 	git reset --hard
> 	git bisect good/bad
> 
> In this case you get merge conflicts in drivers/video/fbdev/amba-clcd.c
> and drivers/video/fbdev/vermilion/vermilion.c. In the assumption that
> you don't have these enabled in your .config, you can just ignore these.
> 
> Side note: A problem during bisection can be that the .config changes
> along the process. You should put your config into (say)
> arch/x86/configs/lala_defconfig and do
> 
> 	make lala_defconfig
> 
> before building each step to prevent this.

I must have done something wrong:

marvin@...iant:~/linux/kernel/linux_torvalds$ git bisect log
# bad: [689237ab37c59b9909bc9371d7fece3081683fba] fbdev/intelfb: Remove driver
# good: [de927f6c0b07d9e698416c5b287c521b07694cac] Merge tag 's390-6.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
git bisect start '689237ab37c5' 'de927f6c0b07d9e698416c5b287c521b07694cac'
# good: [d9f25b59ed85ae45801cf45fe17eb269b0ef3038] fbdev: Remove support for Carillo Ranch driver
git bisect good d9f25b59ed85ae45801cf45fe17eb269b0ef3038
# good: [e2e0b838a1849f92612a8305c09aaf31bf824350] video/sticore: Remove info field from STI struct
git bisect good e2e0b838a1849f92612a8305c09aaf31bf824350
# good: [778e73d2411abc8f3a2d60dbf038acaec218792e] drm/hyperv: Remove firmware framebuffers with aperture helper
git bisect good 778e73d2411abc8f3a2d60dbf038acaec218792e
# good: [df67699c9cb0ceb70f6cc60630ca938c06773eda] firmware/sysfb: Clear screen_info state after consuming it
git bisect good df67699c9cb0ceb70f6cc60630ca938c06773eda
marvin@...iant:~/linux/kernel/linux_torvalds$

with the error:

marvin@...iant:~/linux/kernel/linux_torvalds$ git bisect good
Bisecting: 0 revisions left to test after this (roughly 0 steps)
drivers/video/fbdev/amba-clcd.c: needs merge
drivers/video/fbdev/vermilion/vermilion.c: needs merge
error: you need to resolve your current index first
marvin@...iant:~/linux/kernel/linux_torvalds$

Best regards,
Mirsad

> Best regards
> Uwe
>