What are kjournald and kswapd0 processes?

Question

linux

The server went down hard. What are the processes above?
IOTOP:
280 be/6 root 420.00 K 66632.00 K 0.00 % 72.86 % [kjournald]
76 be/4 root 0.00 K 52.00 K 0.00 % 55.44 % [kswapd0]
264 be/4 root 0.00 K 0.00 K 0.00 % 50.11
1190 be/4 root 0.00K 0.00K 0.00% 33.64% [flush-9:1]
9:1 device is md1

Answer 1

file system journaling
system swap
actually your applications gobbled up all the memory and then started using swap on the disk

Answer 2

I can be wrong, but with swap disabled, kswapd0 can also devour resources when free space in /