[LSF/MM/BPF TOPIC] memory persistence over kexec

[Mike Rapoport <rppt@kernel.org>]

Hi,

I'd like to discuss memory persistence across kexec.

Currently there is ongoing work on Kexec HandOver (KHO) [1] that allows
serialization and deserialization of kernel data as well as preserving
arbitrary memory ranges across kexec.

In addition, KHO keeps a physically contiguous memory regions that are
guaranteed to not have any memory that KHO would preserve, but still can be
used by the system. The kexeced kernel bootstraps itself using those
regions and sets all handed over memory as in use. KHO users then can
recover their state from the preserved data. This includes memory
reservations, where the user can either discard or claim reservations.

KHO can be used as the base layer for implementation of persistence-aware
memory allocator and persistent in-memory filesystem.

Aside from status update on KHO progress there are a few topics that I would
like to discuss:
* Is it feasible and desirable to enable KHO support in tmpfs and hugetlbfs?
* Or is it better to implement yet another in-memory filesystem dedicated
  for persistence?
* What is the best way to ensure that the memory we want to persist is not
  scattered all over the place?

[1] https://lore.kernel.org/all/20240117144704.602-1-graf@amazon.com/

-- 
Sincerely yours,
Mike.