Re: [PATCH 1/3] mm/memory_hotplug: Allow an override for the memmap_on_memory param

[David Hildenbrand]

On 16.06.23 00:00, Vishal Verma wrote:
> For memory hotplug to consider MHP_MEMMAP_ON_MEMORY behavior, the
> 'memmap_on_memory' module parameter was a hard requirement.
>
> In preparation for the dax/kmem driver to use memmap_on_memory
> semantics, arrange for the module parameter check to be bypassed via the
> appropriate mhp_flag.
>
> Recall that the kmem driver could contribute huge amounts of hotplugged
> memory originating from special purposes devices such as CXL memory
> expanders. In some cases memmap_on_memory may be the /only/ way this new
> memory can be hotplugged. Hence it makes sense for kmem to have a way to
> force memmap_on_memory without depending on a module param, if all the
> other conditions for it are met.

Just let the admin configure it. After all, an admin is involved in 
configuring the dax/kmem device to begin with. If add_memory() fails you 
could give a useful hint to the admin.

--
Cheers,

David / dhildenb