Just for the record, someone else was debugging this a few days later: https://bugzilla.kernel.org/show_bug.cgi?id=210241 And proposed a patch, which fixes the issue for both them and me: https://patchwork.kernel.org/project/linux-input/patch/20201119082232.8774-1-felixhaedicke@xxxxxx/ Regards, Merlin On Fri, 6 Nov 2020 06:08:09 +0100, Merlin Büge wrote: > Hi all. > > I think I need some help with debugging an issue I have. > > I recently bought an "Apple Magic Trackpad 2" for reducing strain on my > hand (since I have some RSI[0] issues currently), which is supported in > Linux since version 4.20[1]. > > After connecting it to my laptop it worked instantly at first, but > "sometimes" un- and replugging the trackpad crashes my system. Often it > works fine, but every now and then it triggers `general protection > faults` (often while opening big applications like Firefox), causes my > status bar to hang up, and usually ends in a freeze. Sometimes, just > before the freeze I get thrown back to the console and see a kernel > panic at the end of the log. > > The laptop is a Thinkpad X200 running stock BIOS, Arch Linux and sway, > with microcode updates enabled. I could also reproduce the issue with > Gnome on Wayland. On Xfce I could not reproduce the issue, and also not > on Fedora (which I installed on the same laptop to the same SSD, for > testing). > > I'm using the trackpad only via the USB cable, not via bluetooth. > > Attached is a snippet from the dmesg output with debug logging enabled > (appended `debug` on the kernel cmdline) showing some of the protection > faults. I uploaded the full dmesg output here [2]. In this specific > dmesg output, most of the protection faults happened concurrently while > I was opening Firefox (several times to provoke the crash). A photo of > the kernel panic can be found here [3]. > > This kernel bug report[4] and related arch report[5] seem related to the > issue, maybe it's even the same issue? However, the kernel bug report > mentions that the issue only affects linux >=5.8.7. In my case, I could > reproduce the issue with the following linux versions (installed from > the Arch Linux archive): > > 4.20.0 > 4.20.1 > 4.20.3 > 4.20.7 > 5.0.0 > 5.0.13 > 5.4.74 > 5.2.0 > 5.8.6 > 5.8.7 > 5.8.8 > 5.9.2, 5.9.4 > 5.10rc-2 > > The USB ID of the trackpad is 05ac:0265. > > Because I'm very inexperienced with kernel debugging I would appreciate > any help/pointers to what would be wise to test next. If this is likely > to be an issue with the Linux kernel and not arch-related (unsure, since > I could not reproduce it on other distros), please tell me so and I will > post to the kernel bug tracker instead. > > Thanks! > > Merlin Büge > > > [0]: https://web.eecs.umich.edu/~cscott/rsi.html > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid.git/commit/?h=for-next&id=9d7b18668956c411a422d04c712994c5fdb23a4b > [2]: https://0x0.st/idkH.json > [3]: https://0x0.st/idkz.jpg > [4]: https://bugzilla.kernel.org/show_bug.cgi?id=209239 > [5]: https://bugs.archlinux.org/task/67860 > > > > -- Merlin Büge
