[PATCH] mm: vmscan: split shrink_node() into node part and memcgs part fix

[Johannes Weiner]

As per Roman's suggestion, rename "root" to "target_memcg" to avoid
confusion with the global cgroup root, root_mem_cgroup.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 mm/vmscan.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 65baa89740dd..6199692af434 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2724,16 +2724,16 @@ static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg)
 
 static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
 {
-	struct mem_cgroup *root = sc->target_mem_cgroup;
+	struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
 	struct mem_cgroup *memcg;
 
-	memcg = mem_cgroup_iter(root, NULL, NULL);
+	memcg = mem_cgroup_iter(target_memcg, NULL, NULL);
 	do {
 		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 		unsigned long reclaimed;
 		unsigned long scanned;
 
-		switch (mem_cgroup_protected(root, memcg)) {
+		switch (mem_cgroup_protected(target_memcg, memcg)) {
 		case MEMCG_PROT_MIN:
 			/*
 			 * Hard protection.
@@ -2777,13 +2777,13 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
 			   sc->nr_scanned - scanned,
 			   sc->nr_reclaimed - reclaimed);
 
-	} while ((memcg = mem_cgroup_iter(root, memcg, NULL)));
+	} while ((memcg = mem_cgroup_iter(target_memcg, memcg, NULL)));
 }
 
 static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 {
 	struct reclaim_state *reclaim_state = current->reclaim_state;
-	struct mem_cgroup *root = sc->target_mem_cgroup;
+	struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
 	unsigned long nr_reclaimed, nr_scanned;
 	bool reclaimable = false;
 
@@ -2801,7 +2801,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 	}
 
 	/* Record the subtree's reclaim efficiency */
-	vmpressure(sc->gfp_mask, root, true,
+	vmpressure(sc->gfp_mask, target_memcg, true,
 		   sc->nr_scanned - nr_scanned,
 		   sc->nr_reclaimed - nr_reclaimed);
 
@@ -2857,7 +2857,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 	 */
 	if (cgroup_reclaim(sc) && writeback_throttling_sane(sc) &&
 	    sc->nr.dirty && sc->nr.dirty == sc->nr.congested)
-		set_memcg_congestion(pgdat, root, true);
+		set_memcg_congestion(pgdat, target_memcg, true);
 
 	/*
 	 * Stall direct reclaim for IO completions if underlying BDIs
@@ -2866,7 +2866,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 	 * the LRU too quickly.
 	 */
 	if (!sc->hibernation_mode && !current_is_kswapd() &&
-	    current_may_throttle() && pgdat_memcg_congested(pgdat, root))
+	    current_may_throttle() &&
+	    pgdat_memcg_congested(pgdat, target_memcg))
 		wait_iff_congested(BLK_RW_ASYNC, HZ/10);
 
 	if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed,
-- 
2.23.0