The problem with overcommitting beyond the sum of RAM and swap is that userspace processes can't protect themselves against the kernel's lies. You allocate memo

The problem with overcommitting beyond the sum of RAM and swap is that userspace processes can't protect themselves against the kernel's lies. You allocate memory, handle the result, access the address space and someone dies. The Linux default behaviour is an insane over-optimisation, but without it forking large processes becomes painfully expensive. The proper solution is to spawn directly through suitable system calls instead of the traditional fork() + execve() way. Imo a good compromise to this day is to overcommit RAM with swap as fallback for correctness even if performance falls of a cliff if you use it. All of that is on top of resource limits and usage monitoring.