quoted

Because the window of kernel live update is short, it is difficult to statistics
how many times the kernel is live updated.

Is it possible to add a variable to statistics the times that the kernel is live
updated?

The kernel doesn't do the live update on its own. The process is driven
and sequenced by userspace. So if you want to keep statistics, you
should do it from your userspace (luod maybe?). I don't see any need for
this in the kernel.

One use case I can think of is including information in kdump or the
backtrace warning/panic messages about how many times this machine has
been live-updated. In the past, I've seen bugs (related to memory
corruption) that occurred only after several kexecs, not on the first
one. With live updates, especially while the code is being stabilized,
I imagine we might have a similar situation. For that reason, it could
be useful to have a count in the dmesg logs showing how many times
this machine has been live-updated. While this information is also
available in userspace, it would be simpler for kernel developers
triaging these issues if everything were in one place.

Pasha