mm: clean up mm_counter

Presently, per-mm statistics counter is defined by macro in sched.h

This patch modifies it to
  - defined in mm.h as inlinf functions
  - use array instead of macro's name creation.

This patch is for reducing patch size in future patch to modify
implementation of per-mm counter.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 278cd27..73d0472 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -815,9 +815,9 @@
 
 	if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
 		if (PageAnon(page))
-			dec_mm_counter(mm, anon_rss);
+			dec_mm_counter(mm, MM_ANONPAGES);
 		else
-			dec_mm_counter(mm, file_rss);
+			dec_mm_counter(mm, MM_FILEPAGES);
 		set_pte_at(mm, address, pte,
 				swp_entry_to_pte(make_hwpoison_entry(page)));
 	} else if (PageAnon(page)) {
@@ -839,7 +839,7 @@
 					list_add(&mm->mmlist, &init_mm.mmlist);
 				spin_unlock(&mmlist_lock);
 			}
-			dec_mm_counter(mm, anon_rss);
+			dec_mm_counter(mm, MM_ANONPAGES);
 		} else if (PAGE_MIGRATION) {
 			/*
 			 * Store the pfn of the page in a special migration
@@ -857,7 +857,7 @@
 		entry = make_migration_entry(page, pte_write(pteval));
 		set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
 	} else
-		dec_mm_counter(mm, file_rss);
+		dec_mm_counter(mm, MM_FILEPAGES);
 
 	page_remove_rmap(page);
 	page_cache_release(page);
@@ -996,7 +996,7 @@
 
 		page_remove_rmap(page);
 		page_cache_release(page);
-		dec_mm_counter(mm, file_rss);
+		dec_mm_counter(mm, MM_FILEPAGES);
 		(*mapcount)--;
 	}
 	pte_unmap_unlock(pte - 1, ptl);