mm/page_cgroup.c: mark functions as static

Mark functions as static in page_cgroup.c because they are not used
outside this file.

This eliminates the following warning in mm/page_cgroup.c:

  mm/page_cgroup.c:177:6: warning: no previous prototype for `__free_page_cgroup' [-Wmissing-prototypes]
  mm/page_cgroup.c:190:15: warning: no previous prototype for `online_page_cgroup' [-Wmissing-prototypes]
  mm/page_cgroup.c:225:15: warning: no previous prototype for `offline_page_cgroup' [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_cgroup.c

@@ -175,7 +175,7 @@ static void free_page_cgroup(void *addr)
 	}
 }
 
-void __free_page_cgroup(unsigned long pfn)
+static void __free_page_cgroup(unsigned long pfn)
 {
 	struct mem_section *ms;
 	struct page_cgroup *base;
@@ -188,9 +188,9 @@ void __free_page_cgroup(unsigned long pfn)
 	ms->page_cgroup = NULL;
 }
 
-int __meminit online_page_cgroup(unsigned long start_pfn,
-			unsigned long nr_pages,
-			int nid)
+static int __meminit online_page_cgroup(unsigned long start_pfn,
+				unsigned long nr_pages,
+				int nid)
 {
 	unsigned long start, end, pfn;
 	int fail = 0;
@@ -223,8 +223,8 @@ int __meminit online_page_cgroup(unsigned long start_pfn,
 	return -ENOMEM;
 }
 
-int __meminit offline_page_cgroup(unsigned long start_pfn,
-		unsigned long nr_pages, int nid)
+static int __meminit offline_page_cgroup(unsigned long start_pfn,
+				unsigned long nr_pages, int nid)
 {
 	unsigned long start, end, pfn;