mm: make get_mm_counter static-inline

Make get_mm_counter() always static inline, it is simple enough for that.
And remove unused set_mm_counter()

bloat-o-meter:

add/remove: 0/1 grow/shrink: 4/12 up/down: 99/-341 (-242)
function                                     old     new   delta
try_to_unmap_one                             886     952     +66
sys_remap_file_pages                        1214    1230     +16
dup_mm                                      1684    1700     +16
do_exit                                     2277    2278      +1
zap_page_range                               208     205      -3
unmap_region                                 304     296      -8
static.oom_kill_process                      554     546      -8
try_to_unmap_file                           1716    1700     -16
getrusage                                    925     909     -16
flush_old_exec                              1704    1688     -16
static.dump_header                           416     390     -26
acct_update_integrals                        218     187     -31
do_task_stat                                2986    2954     -32
get_mm_counter                                34       -     -34
xacct_add_tsk                                371     334     -37
task_statm                                   172     118     -54
task_mem                                     383     323     -60

try_to_unmap_one() grows because update_hiwater_rss() now completely inline.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -1058,19 +1058,20 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 /*
  * per-process(per-mm_struct) statistics.
  */
-static inline void set_mm_counter(struct mm_struct *mm, int member, long value)
-{
-	atomic_long_set(&mm->rss_stat.count[member], value);
-}
-
-#if defined(SPLIT_RSS_COUNTING)
-unsigned long get_mm_counter(struct mm_struct *mm, int member);
-#else
 static inline unsigned long get_mm_counter(struct mm_struct *mm, int member)
 {
-	return atomic_long_read(&mm->rss_stat.count[member]);
-}
+	long val = atomic_long_read(&mm->rss_stat.count[member]);
+
+#ifdef SPLIT_RSS_COUNTING
+	/*
+	 * counter is updated in asynchronous manner and may go to minus.
+	 * But it's never be expected number for users.
+	 */
+	if (val < 0)
+		val = 0;
 #endif
+	return (unsigned long)val;
+}
 
 static inline void add_mm_counter(struct mm_struct *mm, int member, long value)
 {

mm/memory.c

@@ -160,24 +160,6 @@ static void check_sync_rss_stat(struct task_struct *task)
 		__sync_task_rss_stat(task, task->mm);
 }
 
-unsigned long get_mm_counter(struct mm_struct *mm, int member)
-{
-	long val = 0;
-
-	/*
-	 * Don't use task->mm here...for avoiding to use task_get_mm()..
-	 * The caller must guarantee task->mm is not invalid.
-	 */
-	val = atomic_long_read(&mm->rss_stat.count[member]);
-	/*
-	 * counter is updated in asynchronous manner and may go to minus.
-	 * But it's never be expected number for users.
-	 */
-	if (val < 0)
-		return 0;
-	return (unsigned long)val;
-}
-
 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
 {
 	__sync_task_rss_stat(task, mm);