Re: [PATCH v8 0/2] kho: add support for deferred struct page init

[Mike Rapoport <rppt@kernel.org>]

On Thu, Apr 16, 2026 at 01:06:52PM +0200, Michal Clapinski wrote:
> When CONFIG_DEFERRED_STRUCT_PAGE_INIT 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.
> ---
> v8:
> - moved overriding the migratetype from init_pageblock_migratetype
>   to callsites
> 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.

Any chance you can clean that monster and send it as patch 3?
There's no real difference between core_initcall() and module_init() with
respect to that deferred page initialization, they both run after the
memory map is fully initialized.

> This patch probably doesn't apply onto anything currently.
> It's based on mm-new with
> "memblock: move reserve_bootmem_range() to memblock.c and make it static"
> cherrypicked from rppt/memblock.

You can base on for-next in the memblock tree:
https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

> Evangelos Petrongonas (1):
>   kho: make preserved pages compatible with deferred struct page init
> 
> Michal Clapinski (1):
>   kho: fix deferred initialization of scratch areas
> 
>  include/linux/memblock.h           |  7 ++--
>  kernel/liveupdate/Kconfig          |  2 --
>  kernel/liveupdate/kexec_handover.c | 52 +++++++++++++++---------------
>  mm/memblock.c                      | 41 +++++++++++------------
>  mm/mm_init.c                       | 27 +++++++++++-----
>  5 files changed, 69 insertions(+), 60 deletions(-)
> 
> -- 
> 2.54.0.rc1.555.g9c883467ad-goog
> 

-- 
Sincerely yours,
Mike.