[BUG] KHO handover hangs when memmap reserves PMEM

[Chris Bainbridge]

On Sun, Oct 04, 2026 at 03:39:25PM +0200, Pratyush Yadav wrote:
> 
> Just to confirm, the first kernel boots without memmap= right?

Yes.

> I think the main problem is that the radix tree pages can be anywhere in
> memory. So on the first kernel, they can land in an area that the second
> kernel's memmap= reserves. So kho_memory_init() might end up using
> memory that memmap= reserved. I'm not sure why exactly the next kernel
> doesn't produce any output, but IIRC memmap= memory is not mapped to the
> direct map, so accessing those pages likely causes a page fault.

That's correct, kho_memory_init() page faults. It happens before the
serial console is available, so there is no output.