Memory reclaim events are currently difficult to attribute to
specific cgroups, making debugging memory pressure issues
challenging.  This patch adds memory cgroup ID (memcg_id) to key
vmscan tracepoints to enable better correlation and analysis.

For operations not associated with a specific cgroup, the field
is defaulted to 0.

Signed-off-by: Thomas Ballasi <redacted>
---
 include/trace/events/vmscan.h | 83 ++++++++++++++++++++---------------
 mm/shrinker.c                 |  6 ++-
 mm/vmscan.c                   | 17 +++----
 3 files changed, 61 insertions(+), 45 deletions(-)

diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index 490958fa10dee..20160e79eb0d7 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h

@@ -114,85 +114,92 @@ TRACE_EVENT(mm_vmscan_wakeup_kswapd,
 
 DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(gfp_t gfp_flags, int order, u64 memcg_id),
 
-	TP_ARGS(order, gfp_flags),
+	TP_ARGS(gfp_flags, order, memcg_id),
 
 	TP_STRUCT__entry(
-		__field(	int,	order		)
 		__field(	unsigned long,	gfp_flags	)
+		__field(	u64,	memcg_id	)
+		__field(	int,	order		)
 	),
 
 	TP_fast_assign(
-		__entry->order		= order;
 		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
+		__entry->order		= order;
+		__entry->memcg_id	= memcg_id;