Hi Salvatore, Thank you for the detailed guide on how to perform the git bisection.
The issue has unexpectedly resolved itself and I can no longer reproduce the fan behavior. I don't want to waste your time with an unreliable bisection, so I will hold off for now. If the bug returns (or if I encounter a new regression in the future), I now know exactly how to provide a proper git bisect log. Thanks again for your help and for your work on Debian. Best regards, Jim man. 19. jan. 2026 kl. 22:06 skrev Salvatore Bonaccorso <[email protected]>: > Control: tags -1 + moreinfo > > Hi, > > On Mon, Jan 19, 2026 at 09:08:11AM +0100, Jim Christian Dale Haukvik wrote: > > Package: src:linux > > Version: 6.12.63-1 > > Severity: important > > X-Debbugs-Cc: [email protected] > > > > Dear Maintainer, > > > > What led up to the situation? > > I upgraded my system from Debian 13.2 to 13.3. This included a kernel > update > > from version 6.12.57 to 6.12.63. > > > > What exactly did you do (or not do) that was effective (or ineffective)? > > I booted into the new kernel (6.12.63). I checked CPU usage using htop, > which > > was normal (under 5%), yet the fan remained at a high, constant speed. > > I then rebooted and selected the previous kernel version (6.12.57) from > the > > GRUB advanced menu. > > > > What was the outcome of this action? > > On kernel 6.12.57, the fan behaves normally (turning off or slowing down > at > > idle). On kernel 6.12.63, the fans are not turning off. > > > > What outcome did you expect instead? > > I expected the fan management to remain functional as they were in the > previous > > kernel version. This appears to be a regression in the 6.12.63 build. > > As, as far I understand you can reliably reproduce the problem, it > would be great if you could bisect the problem. That would involve > compiling and testing a few kernels: > > git clone --single-branch -b linux-6.12.y > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git > cd linux-stable > git checkout v6.12.57 > cp /boot/config-$(uname -r) .config > yes '' | make localmodconfig > make savedefconfig > mv defconfig arch/x86/configs/my_defconfig > > # test 6.12.57 to ensure this is "good" > make my_defconfig > make -j $(nproc) bindeb-pkg > ... install the resulting .deb package and confirm the problem does > not exists > > # test 6.12.63 to ensure this is "bad" > git checkout v6.12.63 > make my_defconfig > make -j $(nproc) bindeb-pkg > ... install the resulting .deb package and confirm the FAN problem > exists > > With that confirmed, the bisection can start: > > git bisect start > git bisect good v6.12.57 > git bisect bad v6.12.63 > > 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 bad > > and if the problem doesn't trigger run: > > git bisect good > > . 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 bad 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. > > Additionally to the above, could you please as well check if the > current version in unstable would expose as well the problem? > > Regards, > Salvatore > -- *Mvh* Jim Christian Dale Haukvik
