diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index f59d797dc5a9b28ddcb3eae0f0aeeb4bc6e6daad..1223d927904d196d652911e222bc4a50140c627b 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -165,7 +165,7 @@ int online_page_cgroup(unsigned long start_pfn,
 	unsigned long start, end, pfn;
 	int fail = 0;
 
-	start = start_pfn & (PAGES_PER_SECTION - 1);
+	start = start_pfn & ~(PAGES_PER_SECTION - 1);
 	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
 
 	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
@@ -188,7 +188,7 @@ int offline_page_cgroup(unsigned long start_pfn,
 {
 	unsigned long start, end, pfn;
 
-	start = start_pfn & (PAGES_PER_SECTION - 1);
+	start = start_pfn & ~(PAGES_PER_SECTION - 1);
 	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
 
 	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)