1 files changed, 1 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ece7b8e8a5b6..df2022ff0c8a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5585,7 +5585,7 @@ static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
         pfn &= (PAGES_PER_SECTION-1);
         return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #else
-        pfn = pfn - zone->zone_start_pfn;
+        pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
         return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #endif /* CONFIG_SPARSEMEM */
 }