Re: [PATCH 2/3] mm/memory_hotplug: activate node before adding new memory blocks

[David Hildenbrand <david@redhat.com>]

On 02.07.25 09:39, Hannes Reinecke wrote:
> The sysfs attributes for memory blocks require the node ID to be
> set and initialized, so move the node activation before adding
> new memory blocks. This also has the nice side effect that the
> BUG_ON() can be converted into a WARN_ON() as we now can handle
> registration errors.
> 
> Fixes: b9ff036082cd ("mm/memory_hotplug.c: make add_memory_resource use __try_online_node")

We should CC stable.

> Signed-off-by: Hannes Reinecke <hare@kernel.org>
> ---
>   drivers/base/memory.c  | 19 +++++++++----------
>   include/linux/memory.h |  2 +-
>   mm/memory_hotplug.c    | 32 +++++++++++++++++---------------
>   3 files changed, 27 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 2b951e5f8a27..d24a90e0ea96 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -810,15 +810,14 @@ void memory_block_add_nid(struct memory_block *mem, int nid,
>   			mem->zone = early_node_zone_for_memory_block(mem, nid);
>   		else
>   			mem->zone = NULL;
> +		/*
> +		 * If this memory block spans multiple nodes, we only indicate
> +		 * the last processed node. If we span multiple nodes (not applicable
> +		 * to hotplugged memory), zone == NULL will prohibit memory offlining
> +		 * and consequently unplug.
> +		 */
> +		mem->nid = nid;
>   	}
> -
> -	/*
> -	 * If this memory block spans multiple nodes, we only indicate
> -	 * the last processed node. If we span multiple nodes (not applicable
> -	 * to hotplugged memory), zone == NULL will prohibit memory offlining
> -	 * and consequently unplug.
> -	 */
> -	mem->nid = nid;

I would not perform this change in this patch. It's not required here, 
right? We're simply re-setting the nid. Patch #3 can clean that up.

Apart from that

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb