Add a trace point to psi_avgs_work().

It can be used to attach a bpf handler which can monitor
PSI values system-wide or for specific cgroup(s) and
potentially perform some actions, e.g. declare an OOM.

Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
---
 include/trace/events/psi.h | 27 +++++++++++++++++++++++++++
 kernel/sched/psi.c         |  6 ++++++
 2 files changed, 33 insertions(+)
 create mode 100644 include/trace/events/psi.h

diff --git a/include/trace/events/psi.h b/include/trace/events/psi.h
new file mode 100644
index 000000000000..57c46de18616
--- /dev/null
+++ b/include/trace/events/psi.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM psi
+
+#if !defined(_TRACE_PSI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PSI_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(psi_avgs_work,
+	TP_PROTO(struct psi_group *group),
+	TP_ARGS(group),
+	TP_STRUCT__entry(
+		__field(struct psi_group *, group)
+	),
+
+	TP_fast_assign(
+		__entry->group = group;
+	),
+
+	TP_printk("group=%p", __entry->group)
+);
+
+#endif /* _TRACE_PSI_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 59fdb7ebbf22..72757ba2ed96 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -141,6 +141,10 @@
 #include <linux/psi.h>
 #include "sched.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/psi.h>
+#undef CREATE_TRACE_POINTS
+
 static int psi_bug __read_mostly;
 
 DEFINE_STATIC_KEY_FALSE(psi_disabled);
@@ -607,6 +611,8 @@ static void psi_avgs_work(struct work_struct *work)
 				group->avg_next_update - now) + 1);
 	}
 
+	trace_psi_avgs_work(group);
+
 	mutex_unlock(&group->avgs_lock);
 }
 
-- 
2.52.0