Re: [PATCH v7 0/3] kho: add support for deferred struct page init

[Mike Rapoport <rppt@kernel.org>]

Hi Michal,

On Tue, Mar 17, 2026 at 03:15:31PM +0100, Michal Clapinski wrote:
> When CONFIG_DEFERRED_STRUCT_PAGE_INIT (hereinafter DEFERRED) is
> enabled, struct page initialization is deferred to parallel kthreads
> that run later in the boot process.
> 
> Currently, KHO is incompatible with DEFERRED.
> This series fixes that incompatibility.
> ---
> v7:
> - reimplemented the initialization of kho scratch again
> v6:
> - reimplemented the initialization of kho scratch
> v5:
> - rebased
> v4:
> - added a new commit to fix deferred init of kho scratch
> - switched to ulong when refering to pfn
> v3:
> - changed commit msg
> - don't invoke early_pfn_to_nid if CONFIG_DEFERRED_STRUCT_PAGE_INIT=n
> v2:
> - updated a comment
> 
> I took Evangelos's test code:
> https://git.infradead.org/?p=users/vpetrog/linux.git;a=shortlog;h=refs/heads/kho-deferred-struct-page-init
> and then modified it to this monster test that does 2 allocations:
> at core_initcall (early) and at module_init (late). Then kexec, then
> 2 more allocations at these points, then restore the original 2, then
> kexec, then restore the other 2. Basically I test preservation of early
> and late allocation both on cold and on warm boot.
> Tested it both with and without DEFERRED.
> 
> Evangelos Petrongonas (1):
>   kho: make preserved pages compatible with deferred struct page init
> 
> Michal Clapinski (2):
>   kho: make kho_scratch_overlap usable outside debugging
>   kho: fix deferred init of kho scratch
> 
>  include/linux/kexec_handover.h              |  6 ++
>  include/linux/memblock.h                    |  2 -
>  kernel/liveupdate/Kconfig                   |  2 -
>  kernel/liveupdate/Makefile                  |  1 -
>  kernel/liveupdate/kexec_handover.c          | 65 ++++++++++++++++++---
>  kernel/liveupdate/kexec_handover_debug.c    | 25 --------
>  kernel/liveupdate/kexec_handover_internal.h |  7 ++-
>  mm/memblock.c                               | 22 -------
>  mm/page_alloc.c                             |  7 +++

Although it's a small change, page_alloc maintainers should be CC'ed
Adding them now.

>  9 files changed, 74 insertions(+), 63 deletions(-)
>  delete mode 100644 kernel/liveupdate/kexec_handover_debug.c
> 
> -- 
> 2.53.0.851.ga537e3e6e9-goog
> 

-- 
Sincerely yours,
Mike.