The OOM killer makes the final memory call
When memory is exhausted, someone has to give. The kernel picks a victim by a policy you can read and influence, turning a crash into an order you can reason about. Exhaustion forces a choice Physical memory runs out, the allocator’s reclaim path has already been walked, and the kernel still cannot satisfy a grant — that is when the out-of-memory killer acts. It is not random; it computes which process to kill using a numeric score and terminates the least valuable candidate under pressure. The score weighs resident memory against a process’s share of the host, so a big, idle service that contributes little can be picked off while a small but essential one is spared. Understanding that the OOM killer runs on a score, not on who arrived first, is the whole basis for predicting its next move. ...