What happens when RAM + Swap runs out?

[harmonyp]

So I have noticed that when swap starts (currently set to swappiness 0) the swap that is taken actually reduces the current RSS memory a virtual machine has. For example if I allocated a virtual machine 10GB of RAM and it peaked at 10GB of RAM the reserved memory for that running machine would remain at 100% until either swap activates or I turn the machine off/on.

What happens when both RAM and swap reaches 100%? Does the RSS memory get taken away from a virtual machine or does some of them virtual machines just get killed from being OOM?

/proc/sys/vm/overcommit_memory

is set to 1

 

[Dunuin]

If you run out of RAM the OOM kicks in and will kill VMs. Overcommiting memory isn't really working, even if you use ballooning.