Re: [PATCH] memory hotadd fixes [4/5] avoid check in acpi

[keith mannthey <kmannth@us.ibm.com>]

On Thu, 2006-08-03 at 12:36 +0900, KAMEZAWA Hiroyuki wrote:
> add_memory() does all necessary check to avoid collision.
> then, acpi layer doesn't have to check region by itself.
> 
> (*) pfn_valid() just returns page struct is valid or not. It returns 0
>     if a section has been already added even is ioresource is not added.
>     ioresource collision check in mm/memory_hotplug.c can do more precise
>     collistion check.
>     added enabled bit check just for sanity check..
> 
> Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

> -		start_pfn = info->start_addr >> PAGE_SHIFT;
> -		end_pfn = (info->start_addr + info->length - 1) >> PAGE_SHIFT;
> -
> -		if (pfn_valid(start_pfn) || pfn_valid(end_pfn)) {

This check needs to go somewhare in the add path.  I am thinking of a
validate_add_memory_area call in add_memory (that can also be flexable
to enable the reserve check of (this memory area in add_nodes).  

  It is a useful protection for the sparsemem add path. I would rather
the kernel be able to stand up to odd acpi namespaces or other
mechanisms of invoking add_memory. 

Thanks,
  Keith