touchpad stops responding to touch after mempressure/swap event
I recently started using libinput 1.15.1 from updating my system. I was trying to scroll a page in Firefox when scrolling suddenly stopped working, and I found that I could no longer move my cursor with the touchpad. Left, middle and right clicks still worked when I physically clicked down. I enabled my mouse and found that the cursor could still move using it.
I posted this issue here because I examined Xorg.0.log and found the following:
[154472.727] (EE) client bug: timer event10 gestures: scheduled expiry is in the past (-73ms), your system is too slow [154474.762] (II) event10 - DELL0810:00 044E:120A Touchpad: SYN_DROPPED event - some input events have been lost. [154474.762] (EE) event10 - DELL0810:00 044E:120A Touchpad: kernel bug: Wrong slot count (5), reducing to 0 [154474.762] (EE) event10 - DELL0810:00 044E:120A Touchpad: kernel bug: touch 0 ended and began in in same frame. [154474.762] (EE) event10 - DELL0810:00 044E:120A Touchpad: libinput bug: Unable to find topmost touch [154474.762] (EE) event10 - DELL0810:00 044E:120A Touchpad: libinput bug: Unable to find topmost touch
I concluded that since the message was from a recent commit (eb6ef9fe), there is a chance system slowness (or something else) could have triggered a case that has been overlooked.
Steps to reproduce
I haven't yet reproduced it, however I believe this to be caused by system slowness from swap usage. My kernel is linux-lts 5.4.18-1. To reproduce the slowness, you could try enabling a large amount of swap on an HDD and performing lots of file IO at ~85% memory usage/with Firefox running. I do not have a capture.
libinput version you encountered the bug on
libinput 1.15.1-1 (Arch Linux)
Device: DELL0810:00 044E:120A Touchpad
Laptop is a Dell Inspiron 15 5770.