Re: pfn_to_nid under CONFIG_SPARSEMEM and CONFIG_NUMA

Yasunori Goto
2005-11-16T03:14:18Z

On Tue, 15 Nov 2005 14:10:03 -0800
Mike Kravetz <kravetz@us.ibm.com> wrote:

> The following code/comment is in <linux/mmzone.h> if SPARSEMEM
> and NUMA are configured.
>
> /*
> * These are _only_ used during initialisation, therefore they
> * can use __initdata ... They could have names to indicate
> * this restriction.
> */
> #ifdef CONFIG_NUMA
> #define pfn_to_nid early_pfn_to_nid
> #endif
>
> However, pfn_to_nid is certainly used in check_pte_range() mm/mempolicy.c.
> I wouldn't be surprised to find more non init time uses if you follow all
> the call chains.
>
> On ppc64, early_pfn_to_nid now only uses __initdata. So, I would expect
> policy code that calls check_pte_range to cause serious problems on ppc64.
>
> Any suggestions on how this should really be structured? I'm thinking
> of removing the above definition of pfn_to_nid to force each architecture
> to provide a (non init only) version.

Yes! I worried about same things.
How is this?

static inline int pfn_to_nid(unsigned long pfn)
{
return page_to_nid(pfn_to_page(pfn));
}

page_to_nid() and pfn_to_page() is well defined.
Probably, this will work on all architecture.
So, just we should check this should be used after that memmap
is initialized.

Bye.

--
Yasunori Goto