[$] Memory persistence over kexec

The kernel's kexec
mechanism allows one kernel to directly boot a new one; it can be
thought of as a sort of kernel equivalent to the execve()
system call. Kexec has a number of uses, including booting a special kernel
to perform dumps after a crash. Normally, one does not expect user-space
processes to survive booting into a new kernel, but that has not stopped
developers from trying to implement that ability. Mike Rapoport ran a
memory-management-track session at the 2025 Linux Storage, Filesystem,
Memory-Management, and BPF Summit to discuss one piece of that problem:
enabling the contents of memory to persist across a kexec handover so that
the new kernel can pick up where the old one left off.