compaction: fix build error in CMA && !COMPACTION

isolate_freepages_block() and isolate_migratepages_range() are used for
CMA as well as compaction so it breaks build for CONFIG_CMA &&
!CONFIG_COMPACTION.

This patch fixes it.

[akpm@linux-foundation.org: add "do { } while (0)", per Mel]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/compaction.c

@@ -17,6 +17,21 @@
 #include <linux/balloon_compaction.h>
 #include "internal.h"
 
+#ifdef CONFIG_COMPACTION
+static inline void count_compact_event(enum vm_event_item item)
+{
+	count_vm_event(item);
+}
+
+static inline void count_compact_events(enum vm_event_item item, long delta)
+{
+	count_vm_events(item, delta);
+}
+#else
+#define count_compact_event(item) do { } while (0)
+#define count_compact_events(item, delta) do { } while (0)
+#endif
+
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
 
 #define CREATE_TRACE_POINTS
@@ -303,10 +318,9 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 	if (blockpfn == end_pfn)
 		update_pageblock_skip(cc, valid_page, total_isolated, false);
 
-	count_vm_events(COMPACTFREE_SCANNED, nr_scanned);
+	count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
 	if (total_isolated)
-		count_vm_events(COMPACTISOLATED, total_isolated);
-
+		count_compact_events(COMPACTISOLATED, total_isolated);
 	return total_isolated;
 }
 
@@ -613,9 +627,9 @@ next_pageblock:
 
 	trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
 
-	count_vm_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+	count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
 	if (nr_isolated)
-		count_vm_events(COMPACTISOLATED, nr_isolated);
+		count_compact_events(COMPACTISOLATED, nr_isolated);
 
 	return low_pfn;
 }
@@ -1110,7 +1124,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 	if (!order || !may_enter_fs || !may_perform_io)
 		return rc;
 
-	count_vm_event(COMPACTSTALL);
+	count_compact_event(COMPACTSTALL);
 
 #ifdef CONFIG_CMA
 	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)