It might be worth looking at the thread linked below, which concentrates on the cause of this reported error…
> Mar 20 10:47:45 fedora kernel: Freezing user space processes ...
> Mar 20 10:47:45 fedora kernel: Freezing of tasks failed after 20.002 seconds (1 tasks refusing to freeze, wq_busy=0):
> Mar 20 10:47:45 fedora kernel: task:gnome-shell state:D stack: 0 pid: 1917 ppid: 1632 flags:0x00000004
> Mar 20 10:47:45 fedora kernel: Call Trace:
Explicitly stopping gnome-shell before suspend and restarting on restore does seem to help.
Neil