09.12.2018 14:13, Carlos E. R. пишет:
The "kswapd0" kernel process was stuck at 25% CPU, so something was trashing like hell, in a loop. Thus starting any process took minutes. I was lucky to even be able to ssh in and finally kill firefox.
25% is likely one logical CPU (or core), i.e. kswapd consumes 100% of allocated CPU resources. kswapd is started (woken up) when memory becomes short and attempts to free some memory. So in your case it looks like it fails to free enough memory (at least for for long time) and is constantly started again. Every time it needs to traverse page list to find candidates to release so it is time consuming. When you stop firefox you free large amount of memory which returns system to normal state. It is impossible to say why it happened from top output alone. sysrq-m output may provide some clue.