memcg: Export memory.events and memory.events.local from cgroupv2 to cgroupv1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4X0YD?from=project-issue
CVE: NA

--------

Export "memory.events" and "memory.events.local" from cgroupv2 to
cgroupv1.

There are some differences between v2 and v1:

1)events of MEMCG_OOM_GROUP_KILL is not included in cgroupv1. Because,
there is no member of memory.oom.group.

2)events of MEMCG_MAX is represented with "limit_in_bytes" in cgroupv1 instead
of memory.max

3)event of oom_kill is include in memory.oom_control. make oom_kill include
its descendants' events and add oom_kill_local include its oom_kill event only.
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/memcontrol.h

@@ -1214,8 +1214,6 @@ static inline void memcg_memory_event(struct mem_cgroup *memcg,
 		else
 			cgroup_file_notify(&memcg->events_file);
 
-		if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
-			break;
 		if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
 			break;
 	} while ((memcg = parent_mem_cgroup(memcg)) &&

mm/memcontrol.c

@@ -4564,6 +4564,9 @@ static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
 	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
 	seq_printf(sf, "oom_kill %lu\n",
 		   atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
+	seq_printf(sf, "oom_kill_local %lu\n",
+		   atomic_long_read(&memcg->memory_events_local[MEMCG_OOM_KILL]));
+
 	return 0;
 }
 
@@ -5124,6 +5127,31 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
 	return nbytes;
 }
 
+static void __memcg_events_show(struct seq_file *m, atomic_long_t *events)
+{
+	seq_printf(m, "low %lu\n", atomic_long_read(&events[MEMCG_LOW]));
+	seq_printf(m, "high %lu\n", atomic_long_read(&events[MEMCG_HIGH]));
+	seq_printf(m, "limit_in_bytes %lu\n",
+		   atomic_long_read(&events[MEMCG_MAX]));
+	seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM]));
+}
+
+static int memcg_events_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+	__memcg_events_show(m, memcg->memory_events);
+	return 0;
+}
+
+static int memcg_events_local_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+	__memcg_events_show(m, memcg->memory_events_local);
+	return 0;
+}
+
 static struct cftype mem_cgroup_legacy_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -5305,6 +5333,18 @@ static struct cftype mem_cgroup_legacy_files[] = {
 		.seq_show = memory_high_show,
 		.write = memory_high_write,
 	},
+	{
+		.name = "events",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.file_offset = offsetof(struct mem_cgroup, events_file),
+		.seq_show = memcg_events_show,
+	},
+	{
+		.name = "events.local",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.file_offset = offsetof(struct mem_cgroup, events_local_file),
+		.seq_show = memcg_events_local_show,
+	},
 	{ },	/* terminate */
 };