On Tue, 18 Oct 2011 10:48:46 -0700, Dave Hansen dave@linux.vnet.ibm.com wrote:
On Tue, 2011-10-18 at 10:26 -0700, Michal Nazarewicz wrote:
You can do this in a more general fashion by checking the zone boundaries and resolving the pfn->page every MAX_ORDER_NR_PAGES. That will not be SPARSEMEM specific.
I've tried doing stuff that way but it ended up with much more code.
I guess instead of:
+static inline bool zone_pfn_same_memmap(unsigned long pfn1, unsigned long pfn2) +{
- return pfn_to_section_nr(pfn1) == pfn_to_section_nr(pfn2);
+}
You could do:
static inline bool zone_pfn_same_maxorder(unsigned long pfn1, unsigned long pfn2) { unsigned long mask = MAX_ORDER_NR_PAGES-1; return (pfn1 & mask) == (pfn2 & mask); }
I think that works. Should be the same code you have now, basically.
Makes sense. It'd require calling pfn_to_page() every MAX_ORDER_NR_PAGES even in memory models that have linear mapping of struct page, but I guess that's not that bad.