memcg: Export memcg.high from cgroupv2 to cgroupv1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4IMAK?from=project-issue
CVE: NA

--------

Export memory.high from cgroupv2 to cgroupv1. Therefore, when the usage
of the memcg is larger than memory.high, some pages will be reclaimed
before return to userland, which will throttle the process.

Only export memory.high number in mem_cgroup_legacy_files and move
related functions in front of mem_cgroup_legacy_files. There is no need
to other changes.

Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Reviewed-by: weiyang wang <wangweiyang2@huawei.com>
Reviewed-by: weiyang wang <wangweiyang2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>

mm/memcontrol.c

@@ -4956,6 +4956,55 @@ static ssize_t memory_low_write(struct kernfs_open_file *of,
 	return nbytes;
 }
 
+static int memory_high_show(struct seq_file *m, void *v)
+{
+	return seq_puts_memcg_tunable(m,
+		READ_ONCE(mem_cgroup_from_seq(m)->memory.high));
+}
+
+static ssize_t memory_high_write(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;
+	bool drained = false;
+	unsigned long high;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &high);
+	if (err)
+		return err;
+
+	page_counter_set_high(&memcg->memory, high);
+
+	for (;;) {
+		unsigned long nr_pages = page_counter_read(&memcg->memory);
+		unsigned long reclaimed;
+
+		if (nr_pages <= high)
+			break;
+
+		if (signal_pending(current))
+			break;
+
+		if (!drained) {
+			drain_all_stock(memcg);
+			drained = true;
+			continue;
+		}
+
+		reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
+							 GFP_KERNEL, true);
+
+		if (!reclaimed && !nr_retries--)
+			break;
+	}
+
+	memcg_wb_domain_size_changed(memcg);
+	return nbytes;
+}
+
 static struct cftype mem_cgroup_legacy_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -5094,6 +5143,12 @@ static struct cftype mem_cgroup_legacy_files[] = {
 		.seq_show = memory_low_show,
 		.write = memory_low_write,
 	},
+	{
+		.name = "high",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_high_show,
+		.write = memory_high_write,
+	},
 	{ },	/* terminate */
 };
 
@@ -6260,55 +6315,6 @@ static u64 memory_current_read(struct cgroup_subsys_state *css,
 	return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE;
 }
 
-static int memory_high_show(struct seq_file *m, void *v)
-{
-	return seq_puts_memcg_tunable(m,
-		READ_ONCE(mem_cgroup_from_seq(m)->memory.high));
-}
-
-static ssize_t memory_high_write(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;
-	bool drained = false;
-	unsigned long high;
-	int err;
-
-	buf = strstrip(buf);
-	err = page_counter_memparse(buf, "max", &high);
-	if (err)
-		return err;
-
-	page_counter_set_high(&memcg->memory, high);
-
-	for (;;) {
-		unsigned long nr_pages = page_counter_read(&memcg->memory);
-		unsigned long reclaimed;
-
-		if (nr_pages <= high)
-			break;
-
-		if (signal_pending(current))
-			break;
-
-		if (!drained) {
-			drain_all_stock(memcg);
-			drained = true;
-			continue;
-		}
-
-		reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
-							 GFP_KERNEL, true);
-
-		if (!reclaimed && !nr_retries--)
-			break;
-	}
-
-	memcg_wb_domain_size_changed(memcg);
-	return nbytes;
-}
-
 static int memory_max_show(struct seq_file *m, void *v)
 {
 	return seq_puts_memcg_tunable(m,