Re: [patch] mm: suppress pfn range output for zones without pages

[David Rientjes <rientjes@google.com>]

On Thu, 11 Feb 2010, Mel Gorman wrote:

> > free_area_init_nodes() emits pfn ranges for all zones on the system.
> > There may be no pages on a higher zone, however, due to memory
> > limitations or the use of the mem= kernel parameter.  For example:
> > 
> > Zone PFN ranges:
> >   DMA      0x00000001 -> 0x00001000
> >   DMA32    0x00001000 -> 0x00100000
> >   Normal   0x00100000 -> 0x00100000
> > 
> > The implementation copies the previous zone's highest pfn, if any, as the
> > next zone's lowest pfn.  If its highest pfn is then greater than the
> > amount of addressable memory, the upper memory limit is used instead.
> > Thus, both the lowest and highest possible pfn for higher zones without
> > memory may be the same.
> > 
> > The output is now suppressed for zones that do not have a valid pfn
> > range.
> > 
> 
> I see no problem with the patch. Was it a major problem or just
> confusing?
> 

It was just confusing, I don't think anybody would be parsing the kernel 
log for this specifically to determine whether ZONE_NORMAL exists :)

> > Cc: Mel Gorman <mel@csn.ul.ie>
> > Signed-off-by: David Rientjes <rientjes@google.com>
> 
> Reviewed-by: Mel Gorman <mel@csn.ul.ie>
> 

Thanks!

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