memcg: introduce per-memcg reclaim interface for cgroup v1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I545DF
CVE: NA

--------------------------------

introduce per-memcg reclaim interface for cgroup v1, and
disable memory reclaim for root memcg.
Signed-off-by: NChen Wandun <chenwandun@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

mm/memcontrol.c

@@ -5152,6 +5152,49 @@ static int memcg_events_local_show(struct seq_file *m, void *v)
 	return 0;
 }
 
+static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
+			      size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned int nr_retries = MAX_RECLAIM_RETRIES;
+	unsigned long nr_to_reclaim, nr_reclaimed = 0;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "", &nr_to_reclaim);
+	if (err)
+		return err;
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
+			mem_cgroup_is_root(memcg))
+		return -EINVAL;
+
+	while (nr_reclaimed < nr_to_reclaim) {
+		unsigned long reclaimed;
+
+		if (signal_pending(current))
+			return -EINTR;
+
+		/* This is the final attempt, drain percpu lru caches in the
+		 * hope of introducing more evictable pages for
+		 * try_to_free_mem_cgroup_pages().
+		 */
+		if (!nr_retries)
+			lru_add_drain_all();
+
+		reclaimed = try_to_free_mem_cgroup_pages(memcg,
+						nr_to_reclaim - nr_reclaimed,
+						GFP_KERNEL, true);
+
+		if (!reclaimed && !nr_retries--)
+			return -EAGAIN;
+
+		nr_reclaimed += reclaimed;
+	}
+
+	return nbytes;
+}
+
 static struct cftype mem_cgroup_legacy_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -5345,6 +5388,10 @@ static struct cftype mem_cgroup_legacy_files[] = {
 		.file_offset = offsetof(struct mem_cgroup, events_local_file),
 		.seq_show = memcg_events_local_show,
 	},
+	{
+		.name = "reclaim",
+		.write = memory_reclaim,
+	},
 	{ },	/* terminate */
 };
 
@@ -6711,46 +6758,6 @@ static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
 	return nbytes;
 }
 
-static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
-			      size_t nbytes, loff_t off)
-{
-	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
-	unsigned int nr_retries = MAX_RECLAIM_RETRIES;
-	unsigned long nr_to_reclaim, nr_reclaimed = 0;
-	int err;
-
-	buf = strstrip(buf);
-	err = page_counter_memparse(buf, "", &nr_to_reclaim);
-	if (err)
-		return err;
-
-	while (nr_reclaimed < nr_to_reclaim) {
-		unsigned long reclaimed;
-
-		if (signal_pending(current))
-			return -EINTR;
-
-		/*
-		 * This is the final attempt, drain percpu lru caches in the
-		 * hope of introducing more evictable pages for
-		 * try_to_free_mem_cgroup_pages().
-		 */
-		if (!nr_retries)
-			lru_add_drain_all();
-
-		reclaimed = try_to_free_mem_cgroup_pages(memcg,
-						nr_to_reclaim - nr_reclaimed,
-						GFP_KERNEL, true);
-
-		if (!reclaimed && !nr_retries--)
-			return -EAGAIN;
-
-		nr_reclaimed += reclaimed;
-	}
-
-	return nbytes;
-}
-
 static struct cftype memory_files[] = {
 	{
 		.name = "current",