[$] Toward a swap abstraction layer

The kernel's swapping code tends to not get much love. Users try to avoidit, and developers often find better things to do with their time thantrying to improve it. At the 2023 LinuxStorage, Filesystem, Memory-Management and BPF Summit, though, YosryAhmed dedicated a memory-management-track session to the problem of theswap layer and what might be done to make it better.