Bug#1111184: linux: Kernel panic on boot with amdgpu driver

[Salvatore Bonaccorso <carnil@debian.org>]

Control: tags -1 + moreinfo

Hi,

On Mon, Aug 25, 2025 at 12:15:02AM +0300, Руслан Семченко wrote:
> Hello, Salvatore. I have completed the tests as requested. I can
> confirm that the 6.13.2-1~exp1 kernel is GOOD, while the
> 6.13~rc7-1~exp1 kernel is BAD.

Thanks, that is good so we have a good range of version narrow enough
to start now the bisect. Here is what you can do next (I updated the
arlier instructions with the now concrete numbers, important is to
redefine the "bisection" terms and then carefully at each step say if
it is "fixed" or "broken");

	git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
        cd linux-stable
        git checkout v6.13.2
	cp /boot/config-$(uname -r) .config
	yes '' | make localmodconfig
	make savedefconfig
	mv defconfig arch/x86/configs/my_defconfig

        # test 6.13.2 to ensure this is "good"
        make my_defconfig
        make -j $(nproc) bindeb-pkg
        ... install the resulting .deb package and confirm it successfully boots / problem does not exist

        # test 6.13~rc7 to ensure this is "bad"
        git checkout v6.13-rc7
        make my_defconfig
        make -j $(nproc) bindeb-pkg
        ... install the resulting .deb package and confirm it fails to boot / problem exists

Once it is confirmed that this affects so as well the version ranges
upstream, we can proceed:

	git bisect start --term-new=fixed --term-old=broken
	git bisect fixed v6.13.2
	git bisect broken v6.13-rc7

(note this is important, as usually git bisect "direction" is to
determine a breaking commit, but here we want to identify a fixing
commit and so the git bisect terms are redifinied to not always have
to "flip" mentally the meaning of bad and good).

In each bisection step git checks out a state between the oldest
known-bad and the newest known-good commit. In each step test using:
 
        make my_defconfig
        make -j $(nproc) bindeb-pkg
        ... install, try to boot / verify if problem exists

and if the problem is hit run:
 
        git bisect broken

and if the problem doesn't trigger run:
 
        git bisect fixed

. Please pay attention to always select the just built kernel for
booting, it won't always be the default kernel picked up by grub.
 
Iterate until git announces to have identified the first 'fixed'
commit.

Then provide the output of
 
        git bisect log
 
In the course of the bisection you might have to uninstall previous
kernels again to not exhaust the disk space in /boot. Also in the end
uninstall all self-built kernels again.

Is this all of enough help for you?

Regards,
Salvatore