There is mlock(2), which is supposed to prevent the memory from being swapped. The problem with that is that the call requires either root or CAP_IPC_LOCK. If

There is mlock(2), which is supposed to prevent the memory from being swapped. The problem with that is that the call requires either root or CAP_IPC_LOCK. If your user lacks the capability, you have to run the program setuid root. Allocate the sensitive buffers at the start, call mlock() on them and only then drop the privileges. There's also the 10kg fine-tuning hammer, mlockall(2). That makes ALL the memory for the calling process to become unswappable. As it can lock either the "currently held" memory, or "all the memory to be allocated during process lifetime", it can provide for some additional amusement under memory pressure.