Re: [PATCH v4] mm/memory_hotplug: refrain from adding memory into an impossible node

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Thu, 2020-04-16 at 19:12 +0200, David Hildenbrand wrote:
> On 16.04.20 19:10, Vishal Verma wrote:
> > 
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index 0a54ffac8c68..ddd3347edd54 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1005,6 +1005,11 @@ int __ref add_memory_resource(int nid, struct resource *res)
> >  	if (ret)
> >  		return ret;
> >  
> > +	if (!node_possible(nid)) {
> > +		WARN(1, "node %d was absent from the node_possible_map\n", nid);
> > +		return -ENXIO;
> 
> Nit: I suggest using "-EINVAL" instead (e.g., returned via
> check_hotplug_memory_range).
> 
> Not sure if we should pr_err() instead of WARN (see e.g.,
> check_hotplug_memory_range)
> 
Hm, I'm happy to make the changes, but EINVAL to me suggests there is a
problem in the way this was called by the user. And in this case there
really might not be much the user can change in case fo buggy firmware.

Same thing with the WARN - make the potential firmware bug much more
obvious and visible.