Re: [PATCH v5 17/22] mm/mm_init: don't rely on memblock to get KHO scratch migratetype

On Wed, Jul 29, 2026 at 04:56:02PM +0200, Pratyush Yadav wrote:
> From: "Pratyush Yadav (Google)" <[email protected]>
> 
> Currently struct page init via memmap_init() or deferred_init_memmap()
> only queries the migrate type from KHO for each discrete memory range.
> That works currently since KHO scratch memory has a different memory
> type so it is always it its own region.
> 
> An upcoming patch will add support for discovering blocks of memory with
> no preservations and it will mark it as MEMBLOCK_KHO_SCRATCH to allow
> allocations from them. This can lead to the bootmem KHO scratch areas to
> be merged into larger free ranges. This merging breaks the selection of
> migrate type.
> 
> Get rid of memblock_is_kho_scratch_memory(). Instead, use
> kho_scratch_overlap() to decide the migrate type of the PFN. Since
> kho_scratch_migratetype() only uses KHO functions, move it to
> kexec_handover.h.
> 
> Instead of calling kho_scratch_migratetype() once for each free range,
> call it once for each pageblock. Update
> pageblock_migratetype_init_range() and memmap_init_range() to do so.
> 
> Since the migrate type is now evaluated for each pageblock and not each
> free range, drop the migratetype arguments to deferred_free_pages() and
> memmap_init_zone_range() and use MIGRATE_MOVABLE directly.
> 
> Signed-off-by: Pratyush Yadav (Google) <[email protected]>
> ---
>  include/linux/kexec_handover.h | 15 +++++++++++++++
>  include/linux/memblock.h       | 19 -------------------
>  mm/memblock.c                  | 10 ----------
>  mm/mm_init.c                   | 27 +++++++++++++--------------
>  4 files changed, 28 insertions(+), 43 deletions(-)
> 
> diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h
> index 18ba417f1ada..c83ec4a15fe7 100644
> --- a/include/linux/kexec_handover.h
> +++ b/include/linux/kexec_handover.h
> @@ -5,6 +5,7 @@
>  #include <linux/err.h>
>  #include <linux/errno.h>
>  #include <linux/types.h>
> +#include <linux/mmzone.h>

Should have been mm.h, kbuild bot is unhappy otherwise :)

https://lore.kernel.org/all/[email protected]

I can fix it while applying.

-- 
Sincerely yours,
Mike.