A new bug can be filed here: https://bugs.freedesktop.org/enter_bug.cgi?product=Wayland&component=libinput

When reporting bugs against libinput, please follow the instructions below and provide the required data. This will speed up triage, resulting in a quicker bugfix.

First, try to identify the bug by reproducing it reliably. The more specific a bug description is, the easier it is to fix. The libinput-debug-events helper tool can help identify whether the bug is in libinput at all. This tool is a direct hook to libinput without a desktop stack in between and can thus help to identify whether a bug is in libinput or in one of the higher layers. See the libinput-debug-events section for information on this tool.

Required information for triage

When you file a bug, please attach the following information:

a virtual description of your input device, see Recording devices with evemu. This is the most important piece of information, do not forget it!
the libinput version. Either the package version from your distribution or, when running from git: git log -n 1 HEAD or git describe HEAD. As a last resort: libinput-list-devices –version.
the current libinput settings for the device. This is a bit harder to obtain, for now we'll assume you are running X11. The current settings can be obtained with xinput list-props "your device name". Use xinput list to obtain the device name.
if the device is a touchpad or a pointing stick, the vendor model number of your laptop, and the content of /sys/class/dmi/id/modalias.
if the device is a touchpad, the physical dimensions of your touchpad in mm

Recording devices with evemu

evemu records the device capabilities together with the event stream from the kernel. On our side, this allows us to recreate a virtual device identical to your device and re-play the event sequence, hopefully triggering the same bug.

evemu-record takes a /dev/input/eventX event node, but without arguments it will simply show the list of devices and let you select:

$ sudo evemu-record > scroll.evemu
Available devices:
/dev/input/event0:      Lid Switch
/dev/input/event1:      Sleep Button
/dev/input/event2:      Power Button
/dev/input/event3:      AT Translated Set 2 keyboard
/dev/input/event4:      SynPS/2 Synaptics TouchPad
/dev/input/event5:      Video Bus
/dev/input/event6:      ELAN Touchscreen
/dev/input/event10:     ThinkPad Extra Buttons
/dev/input/event11:     HDA Intel HDMI HDMI/DP,pcm=3
/dev/input/event12:     HDA Intel HDMI HDMI/DP,pcm=7
/dev/input/event13:     HDA Intel HDMI HDMI/DP,pcm=8
/dev/input/event14:     HDA Intel PCH Dock Mic
/dev/input/event15:     HDA Intel PCH Mic
/dev/input/event16:     HDA Intel PCH Dock Headphone
/dev/input/event17:     HDA Intel PCH Headphone
/dev/input/event18:     Integrated Camera
/dev/input/event19:     TPPS/2 IBM TrackPoint
Select the device event number [0-19]:

Select the device that triggers the issue, then reproduce the bug and Ctrl+C the process. The resulting recording, ("scroll.evemu" in this example) will contain the sequence required to reproduce the bug. If the bug fails to reproduce during recording, simply Ctrl+C and restart evemu-record. Always start the recording from a neutral state, i.e. without any buttons or keys down, with the position of the device in the neutral position, without touching the screen/touchpad.

Note: The longer the recording, the harder it is to identify the event sequence triggering the bug. Please keep the event sequence as short as possible.

To verify that the recording contains the bug, you can replay it on your device. For example, to replay the sequence recorded in the example above:

$ sudo evemu-play /dev/input/event4 < scroll.evemu

If the bug is triggered by replaying on your device, attach the recording to the bug report.

Note: libinput does not affect the evemu recording. libinput and evemu talk directly to the kernel's device nodes. An evemu recording is not influenced by the libinput version or whether a libinput context is currently active.