linux-kernel - [v10 PATCH 12/13] mm: memcontrol: reparent nr

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Message-Id: <20210311190845.9708-13-shy828301@gmail.com>
Date:   Thu, 11 Mar 2021 11:08:44 -0800
From:   Yang Shi <shy828301@...il.com>
To:     guro@...com, ktkhai@...tuozzo.com, vbabka@...e.cz,
        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: [v10 PATCH 12/13] mm: memcontrol: reparent nr_deferred when memcg offline

Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add to parent's
corresponding nr_deferred when memcg offline.

Acked-by: Vlastimil Babka <vbabka@...e.cz>
Acked-by: Kirill Tkhai <ktkhai@...tuozzo.com>
Acked-by: Roman Gushchin <guro@...com>
Reviewed-by: Shakeel Butt <shakeelb@...gle.com>
Signed-off-by: Yang Shi <shy828301@...il.com>
---
 include/linux/memcontrol.h |  1 +
 mm/memcontrol.c            |  1 +
 mm/vmscan.c                | 24 ++++++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 24e735434a46..4064c9dda534 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1537,6 +1537,7 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
 int alloc_shrinker_info(struct mem_cgroup *memcg);
 void free_shrinker_info(struct mem_cgroup *memcg);
 void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id);
+void reparent_shrinker_deferred(struct mem_cgroup *memcg);
 #else
 #define mem_cgroup_sockets_enabled 0
 static inline void mem_cgroup_sk_alloc(struct sock *sk) { };
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 35d44afdd9fc..a945dfc85156 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5167,6 +5167,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
 	page_counter_set_low(&memcg->memory, 0);
 
 	memcg_offline_kmem(memcg);
+	reparent_shrinker_deferred(memcg);
 	wb_memcg_offline(memcg);
 
 	drain_all_stock(memcg);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 324c34c6e5cf..d0791ebd6761 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -397,6 +397,30 @@ static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
 	return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]);
 }
 
+void reparent_shrinker_deferred(struct mem_cgroup *memcg)
+{
+	int i, nid;
+	long nr;
+	struct mem_cgroup *parent;
+	struct shrinker_info *child_info, *parent_info;
+
+	parent = parent_mem_cgroup(memcg);
+	if (!parent)
+		parent = root_mem_cgroup;
+
+	/* Prevent from concurrent shrinker_info expand */
+	down_read(&shrinker_rwsem);
+	for_each_node(nid) {
+		child_info = shrinker_info_protected(memcg, nid);
+		parent_info = shrinker_info_protected(parent, nid);
+		for (i = 0; i < shrinker_nr_max; i++) {
+			nr = atomic_long_read(&child_info->nr_deferred[i]);
+			atomic_long_add(nr, &parent_info->nr_deferred[i]);
+		}
+	}
+	up_read(&shrinker_rwsem);
+}
+
 static bool cgroup_reclaim(struct scan_control *sc)
 {
 	return sc->target_mem_cgroup;
-- 
2.26.2