[java-man]

I agree, there should exists explicit OS mechanisms to prevent leakage, be it via DMA, paging, or any other way.

In the absence of such mechanisms, especially when mlock() is unavailable (if running a Java app, for example), the app designer can use tricks like one described above to increase the level of difficulty for an attacker. It is not a solution, but an additional countermeasure.

[potatosareok]

You can disable paging if you really care about that but setting swapiness to 0.

Or use something like https://github.com/LucidWorks/mlockall-agent