Re: [rfc 05/10] Sparsemem: Vmemmap does not need section bits

[Christoph Lameter <clameter@sgi.com>]

On Sat, 1 Mar 2008, KAMEZAWA Hiroyuki wrote:

> I like this change. BTW, could you add following change ?
> (or drop this function in sparsemem-vmemmap.)

I cannot find the function in mm/spase-vmemmap.c
 
> == /inclurde/linux/mm.h==
> #ifndef CONFIG_SPARSEMEM_VMEMMAP
> static inline unsigned long page_to_section(struct page *page)
> {
> 	return pfn_to_section(page_to_pfn(page));
> }
> #else
> static inline unsigned long page_to_section(struct page *page)
> {
>         return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
> }
> #endif

Not sure what this means. If we have CONFIG_SPARSEMEM_VMEMMAP then 
SECTION_MASK == 0. So this would reduce to

#ifndef CONFIG_SPARSEMEM_VMEMMAP
static inline unsigned long page_to_section(struct page *page)
{
       return pfn_to_section(page_to_pfn(page));
}
#else
static inline unsigned long page_to_section(struct page *page)
{
         return 0;
}
#endif

Do you propose to also remove the use of the section bits for regular (non 
vmemmap) sparsemem?

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