[PATCH v3 1/2] memory-hotplug: introduce CONFIG_HAVE_BOOTMEM_INFO_NODE and revert register_page_bootmem_info_node() when platform not support

[Michal Hocko]

On Wed 16-01-13 16:14:18, Lin Feng wrote:
[...]
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 278e3ab..f8c5799 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -162,10 +162,18 @@ config MOVABLE_NODE
>  	  Say Y here if you want to hotplug a whole node.
>  	  Say N here if you want kernel to use memory on all nodes evenly.
>  
> +#
> +# Only be set on architectures that have completely implemented memory hotplug
> +# feature. If you are not sure, don't touch it.
> +#
> +config HAVE_BOOTMEM_INFO_NODE
> +	def_bool n
> +
>  # eventually, we can have this option just 'select SPARSEMEM'
>  config MEMORY_HOTPLUG
>  	bool "Allow for memory hot-add"
>  	select MEMORY_ISOLATION
> +	select HAVE_BOOTMEM_INFO_NODE if X86_64
>  	depends on SPARSEMEM || X86_64_ACPI_NUMA
>  	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
>  	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)

I am still not sure I understand the relation to MEMORY_HOTREMOVE.
Is register_page_bootmem_info_node required/helpful even if
!CONFIG_MEMORY_HOTREMOVE?

Also, now that I am thinking about that more, maybe it would
be cleaner to put the select into arch/x86/Kconfig and do it
same as ARCH_ENABLE_MEMORY_{HOTPLUG,HOTREMOVE} (and name it
ARCH_HAVE_BOOTMEM_INFO_NODE).
-- 
Michal Hocko
SUSE Labs