per-zone and reclaim enhancements for memory controller: add scan_glo…

…bal_lru macro

This is used to detect which scan_control scans global lru or mem_cgroup lru.
And compiled to be static value (1) when memory controller is not configured.
This may make the meaning obvious.

Acked-by: Balbir Singh <[email protected]>
Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Herbert Poetzl <[email protected]>
Cc: Kirill Korotaev <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Paul Menage <[email protected]>
Cc: Pavel Emelianov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Vaidyanathan Srinivasan <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/vmscan.c

@@ -126,6 +126,12 @@ long vm_total_pages;	/* The total number of pages which the VM controls */
 static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
 
+#ifdef CONFIG_CGROUP_MEM_CONT
+#define scan_global_lru(sc)	(!(sc)->mem_cgroup)
+#else
+#define scan_global_lru(sc)	(1)
+#endif
+
 /*
  * Add a shrinker callback to be called from the vm
  */
@@ -1280,11 +1286,12 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
 		 * Don't shrink slabs when reclaiming memory from
 		 * over limit cgroups
 		 */
-		if (sc->mem_cgroup == NULL)
+		if (scan_global_lru(sc)) {
 			shrink_slab(sc->nr_scanned, gfp_mask, lru_pages);
-		if (reclaim_state) {
-			nr_reclaimed += reclaim_state->reclaimed_slab;
-			reclaim_state->reclaimed_slab = 0;
+			if (reclaim_state) {
+				nr_reclaimed += reclaim_state->reclaimed_slab;
+				reclaim_state->reclaimed_slab = 0;
+			}
 		}
 		total_scanned += sc->nr_scanned;
 		if (nr_reclaimed >= sc->swap_cluster_max) {
@@ -1311,7 +1318,7 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
 			congestion_wait(WRITE, HZ/10);
 	}
 	/* top priority shrink_caches still had more to do? don't OOM, then */
-	if (!sc->all_unreclaimable && sc->mem_cgroup == NULL)
+	if (!sc->all_unreclaimable && scan_global_lru(sc))
 		ret = 1;
 out:
 	/*