Re: [PATCH v4] memory_hotplug: Add a bounds check to __add_pages

[Oscar Salvador <osalvador@suse.de>]

On Thu, Sep 26, 2019 at 11:34:05AM +1000, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> @@ -291,6 +307,10 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
>  	unsigned long nr, start_sec, end_sec;
>  	struct vmem_altmap *altmap = restrictions->altmap;
>  
> +	err = check_hotplug_memory_addressable(pfn, nr_pages);
> +	if (err)
> +		return err;
> +

I am probably off here because 1) I am jumping blind in a middle of a discussion and
2) I got back from holydays yesterday, so bear with me.

Would not be better to just place the check in add_memory_resource instead?
Take into account that we create the memory mapping for this range in
arch_add_memory, so it looks weird to me to create the mapping if we are going to
fail right after because the range is simply off.

But as I said, I might be missing some previous discussion. 

-- 
Oscar Salvador
SUSE L3