Yesterday, when closing my laptop, it did not go into standby mode immediately. According to the logs, it was trying to, but a tasks refused to freeze:
Freezing of tasks failed after 20.005 seconds (1 tasks refusing to freeze, wq_busy=0):
This went on for a few hours until the system actually suspended. The
syslog was full of messages like in this question, because
systemd was trying again and again.
How can this happen? Why can't the scheduler just stop scheduling that application? and then it's effectively frozen? I read that there are multiple
STOP commands, one of them asking nicely and one of them forcing freeze. Why did
systemd not use this or why did this not work here?