Unable to kill applications

[DarkTrick]

Summary
========
In certain situation, applications cannot be killed anymore. That is:
- Killing via a task manager won't work
- Killing via `killall [app]` won't work
- Killing via `killall -s [yourfavouritesignal] [app]` won't work

This also results in shutdown-problems, because even the system cannot kill the app.
 ( The only solution I found so far is to hardware-reboot the system. )

Suggestion
==========
The kill signal should be honored by the system in every case.

Steps I did
===========
- I had mousepad already
- I downloaded `https://addons.mozilla.org/firefox/downloads/file/3755484/google_search_filter-2.1.11-fx.xpi`
- I renamed it to [...].zip
- I opened it in `Engrampa`
- I opened folder `background`
- I double clicked `background.js`

Notes
=======
- If you check the dmesg log, you can see several `40720.856917] INFO: task mousepad:6357 blocked for more than [x] seconds` messages.

- I would guess this is some IO-related / kernel-related problem, but I'm not sure.

lsb_release -rd
================
Description: Ubuntu 20.10
Release: 20.10

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: linux-image-5.8.0-52-generic 5.8.0-52.59
ProcVersionSignature: Ubuntu 5.8.0-52.59-generic 5.8.18
Uname: Linux 5.8.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu50.6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: nimono 1680 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Sat May 8 20:07:31 2021
MachineType: FUJITSU FMVWB3U27
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-52-generic root=UUID=fe637d00-125b-4a54-adce-3711830d450b ro acpi_osi=! "acpi_osi=Windows 2015" resume=UUID=bdfdad69-4c0d-4b99-a962-d88c977da8a3
RelatedPackageVersions:
 linux-restricted-modules-5.8.0-52-generic N/A
 linux-backports-modules-5.8.0-52-generic N/A
 linux-firmware 1.190.5
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/23/2018
dmi.bios.release: 1.7
dmi.bios.vendor: FUJITSU // Insyde Software Corp.
dmi.bios.version: Version 1.07
dmi.board.name: FJNB2BB
dmi.board.vendor: FUJITSU
dmi.board.version: A2
dmi.chassis.type: 10
dmi.chassis.vendor: FUJITSU
dmi.modalias: dmi:bvnFUJITSU//InsydeSoftwareCorp.:bvrVersion1.07:bd01/23/2018:br1.7:svnFUJITSU:pnFMVWB3U27:pvr:rvnFUJITSU:rnFJNB2BB:rvrA2:cvnFUJITSU:ct10:cvr:
dmi.product.family: LIFEBOOK-JR
dmi.product.name: FMVWB3U27
dmi.sys.vendor: FUJITSU

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.