Re: [PATCH v3 02/30] kho: mm: Don't allow deferred struct page with KHO

[Pratyush Yadav]

On Thu, Aug 07 2025, Pasha Tatashin wrote:

> KHO uses struct pages for the preserved memory early in boot, however,
> with deferred struct page initialization, only a small portion of
> memory has properly initialized struct pages.
>
> This problem was detected where vmemmap is poisoned, and illegal flag
> combinations are detected.
>
> Don't allow them to be enabled together, and later we will have to
> teach KHO to work properly with deferred struct page init kernel
> feature.
>
> Fixes: 990a950fe8fd ("kexec: add config option for KHO")
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>

Nit: Drop the blank line before fixes. git interpret-trailers doesn't
seem to recognize the fixes otherwise, so this may break some tooling.
Try it yourself:

    $ git interpret-trailers --parse commit_message.txt

Other than this,

Acked-by: Pratyush Yadav <pratyush@xxxxxxxxxx>

> Acked-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> ---
>  kernel/Kconfig.kexec | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
> index 2ee603a98813..1224dd937df0 100644
> --- a/kernel/Kconfig.kexec
> +++ b/kernel/Kconfig.kexec
> @@ -97,6 +97,7 @@ config KEXEC_JUMP
>  config KEXEC_HANDOVER
>  	bool "kexec handover"
>  	depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
> +	depends on !DEFERRED_STRUCT_PAGE_INIT
>  	select MEMBLOCK_KHO_SCRATCH
>  	select KEXEC_FILE
>  	select DEBUG_FS

-- 
Regards,
Pratyush Yadav