Comment 6 for bug 1712858

Yes, swapping is the responsibility of the kernel. So if your system occasionally thrashing then that could cause this bug per comment #3. It would also explain why the system is able to recover after some minutes...

Please continue testing but it sounds like the memory hog is the real bug (plasmashell or others). But that said, using several GB of "virtual memory" (VSZ in ps) is not a bug. That's just address space and does not imply any real memory or swap usage. Please monitor RSS (resident set size) instead to see what's impacting the hardware most (run 'ps aux').