What does the out of memory killer do?

The out of memory killer, often referred to as "OOM killer," is a feature in the Linux kernel designed to handle situations where the system is critically low on memory. When available RAM is exhausted, the OOM killer intervenes to free up memory by terminating one or more processes. It selects processes to kill based on various criteria, including their RAM usage, to free up enough memory to ensure that the system remains stable and operational.

While it is true that the OOM killer targets processes that are consuming excess memory, it specifically prioritizes which processes to terminate based on their overall resource consumption, which helps to maintain system integrity when memory is scarce. This behavior is crucial for avoiding system crashes and ensuring that the remaining processes can continue to operate effectively.

The other options presented do not accurately describe the role of the OOM killer. It does not manage swap space directly or alter the size of the swap partition. Additionally, it has no functionality related to recovering or managing passwords, including the root password. Therefore, the focus on how the OOM killer manages processes based on their RAM usage correctly outlines its primary function within the Linux operating system.