Re: [PATCH v1 3/6] mm/memory_hotplug: restrict CONFIG_MEMORY_HOTPLUG to 64 bit

Oscar Salvador
2021-10-07T09:02:20Z

On Wed, Sep 29, 2021 at 04:35:57PM +0200, David Hildenbrand wrote:
> 32 bit support is broken in various ways: for example, we can online
> memory that should actually go to ZONE_HIGHMEM to ZONE_MOVABLE or in
> some cases even to one of the other kernel zones.
>
> We marked it BROKEN in commit b59d02ed0869 ("mm/memory_hotplug: disable the
> functionality for 32b") almost one year ago. According to that commit
> it might be broken at least since 2017. Further, there is hardly a sane use
> case nowadays.
>
> Let's just depend completely on 64bit, dropping the "BROKEN" dependency to
> make clear that we are not going to support it again. Next, we'll remove
> some HIGHMEM leftovers from memory hotplug code to clean up.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

> ---
> mm/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ea8762cd8e1e..88273dd5c6d6 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -125,7 +125,7 @@ config MEMORY_HOTPLUG
> select MEMORY_ISOLATION
> depends on SPARSEMEM
> depends on ARCH_ENABLE_MEMORY_HOTPLUG
> - depends on 64BIT || BROKEN
> + depends on 64BIT
> select NUMA_KEEP_MEMINFO if NUMA
>
> config MEMORY_HOTPLUG_DEFAULT_ONLINE
> --
> 2.31.1
>
>

--
Oscar Salvador
SUSE Labs