linux-kernel - [v3 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map

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Date:   Tue,  5 Jan 2021 14:58:10 -0800
From:   Yang Shi <shy828301@...il.com>
To:     guro@...com, ktkhai@...tuozzo.com, shakeelb@...gle.com,
        david@...morbit.com, hannes@...xchg.org, mhocko@...e.com,
        akpm@...ux-foundation.org
Cc:     shy828301@...il.com, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [v3 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size

Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the
map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both.
Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the
bit map.

Signed-off-by: Yang Shi <shy828301@...il.com>
---
 mm/vmscan.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index ddb9f972f856..8da765a85569 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -185,8 +185,7 @@ static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
 
 #ifdef CONFIG_MEMCG
-
-static int memcg_shrinker_map_size;
+static int shrinker_nr_max;
 
 static void memcg_free_shrinker_map_rcu(struct rcu_head *head)
 {
@@ -248,7 +247,7 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
 		return 0;
 
 	down_read(&shrinker_rwsem);
-	size = memcg_shrinker_map_size;
+	size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long);
 	for_each_node(nid) {
 		map = kvzalloc(sizeof(*map) + size, GFP_KERNEL);
 		if (!map) {
@@ -269,7 +268,7 @@ static int memcg_expand_shrinker_maps(int new_id)
 	struct mem_cgroup *memcg;
 
 	size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
-	old_size = memcg_shrinker_map_size;
+	old_size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long);
 	if (size <= old_size)
 		return 0;
 
@@ -286,10 +285,8 @@ static int memcg_expand_shrinker_maps(int new_id)
 			goto out;
 		}
 	} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
-out:
-	if (!ret)
-		memcg_shrinker_map_size = size;
 
+out:
 	return ret;
 }
 
@@ -321,7 +318,6 @@ void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
 #define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
 
 static DEFINE_IDR(shrinker_idr);
-static int shrinker_nr_max;
 
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 {
-- 
2.26.2