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Date: Fri, 11 Jan 2013 11:47:59 +0100
From: Michal Hocko <mhocko@suse.cz>
Subject: Re: mmots: memory-hotplug: implement
 register_page_bootmem_info_section of sparse-vmemmap fix
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On Fri 11-01-13 11:29:24, Michal Hocko wrote:
> On Fri 11-01-13 11:17:45, Michal Hocko wrote:
> [...]
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index be2b90c..59eddff 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -128,6 +128,64 @@ void __ref put_page_bootmem(struct page *page)
> >  
> >  }
> >  
> > +void register_page_bootmem_memmap(unsigned long section_nr,
> > +				  struct page *start_page, unsigned long size)
> > +{
> > +	unsigned long addr = (unsigned long)start_page;
> > +	unsigned long end = (unsigned long)(start_page + size);
> > +	unsigned long next;
> > +	pgd_t *pgd;
> > +	pud_t *pud;
> > +	pmd_t *pmd;
> > +	unsigned int nr_pages;
> > +	struct page *page;
> > +
> > +	for (; addr < end; addr = next) {
> > +		pte_t *pte = NULL;
> > +
> > +		pgd = pgd_offset_k(addr);
> > +		if (pgd_none(*pgd)) {
> > +			next = (addr + PAGE_SIZE) & PAGE_MASK;
> > +			continue;
> > +		}
> > +		get_page_bootmem(section_nr, pgd_page(*pgd), MIX_SECTION_INFO);
> > +
> > +		pud = pud_offset(pgd, addr);
> > +		if (pud_none(*pud)) {
> > +			next = (addr + PAGE_SIZE) & PAGE_MASK;
> > +			continue;
> > +		}
> > +		get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
> > +
> > +		if (!cpu_has_pse) {
> 
> Darn! And now that I am looking at the patch closer it is too x86
> centric so this cannot be in the generic code. I will try to cook
> something better. Sorry about the noise.

It is more complicated than I thought. One would tell it's a mess.
The patch bellow fixes the compilation issue but I am not sure we want
to include memory_hotplug.h into arch/x86/mm/init_64.c. Moreover

+void register_page_bootmem_memmap(unsigned long section_nr,
+				  struct page *start_page, unsigned long size)
+{
+	/* TODO */
+}

for other archs would suggest that the code is not ready yet. Should
this rather be dropped for now?
---