[PATCH v2 1/2] mm: memcg: print out cgroup name in the memcg tracepoints

[Dmitry Rokosov]

Sometimes it is necessary to understand in which memcg tracepoint event
occurred. The function cgroup_name() is a useful tool for this purpose.
To integrate cgroup_name() into the existing memcg tracepoints, this
patch introduces a new tracepoint template for the begin() and end()
events, utilizing static __array() to store the cgroup name.

Signed-off-by: Dmitry Rokosov <ddrokosov@xxxxxxxxxxxxxxxxx>
---
 include/trace/events/vmscan.h | 77 +++++++++++++++++++++++++++++------
 mm/vmscan.c                   | 10 ++---
 2 files changed, 70 insertions(+), 17 deletions(-)

diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index d2123dd960d5..9b49cd120ae9 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -141,19 +141,47 @@ DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_direct_reclaim_b
 );
 
 #ifdef CONFIG_MEMCG
-DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+DECLARE_EVENT_CLASS(mm_vmscan_memcg_reclaim_begin_template,
 
-	TP_ARGS(order, gfp_flags)
+	TP_PROTO(int order, gfp_t gfp_flags, const struct mem_cgroup *memcg),
+
+	TP_ARGS(order, gfp_flags, memcg),
+
+	TP_STRUCT__entry(
+		__field(int, order)
+		__field(unsigned long, gfp_flags)
+		__array(char, name, NAME_MAX + 1)
+	),
+
+	TP_fast_assign(
+		__entry->order = order;
+		__entry->gfp_flags = (__force unsigned long)gfp_flags;
+		cgroup_name(memcg->css.cgroup,
+			__entry->name,
+			sizeof(__entry->name));
+	),
+
+	TP_printk("order=%d gfp_flags=%s memcg=%s",
+		__entry->order,
+		show_gfp_flags(__entry->gfp_flags),
+		__entry->name)
 );
 
-DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_softlimit_reclaim_begin,
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(int order, gfp_t gfp_flags, const struct mem_cgroup *memcg),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(order, gfp_flags, memcg)
+);
+
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_begin_template, mm_vmscan_memcg_softlimit_reclaim_begin,
+
+	TP_PROTO(int order, gfp_t gfp_flags, const struct mem_cgroup *memcg),
+
+	TP_ARGS(order, gfp_flags, memcg)
 );
+
 #endif /* CONFIG_MEMCG */
 
 DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_end_template,
@@ -181,19 +209,44 @@ DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_direct_reclaim_end
 );
 
 #ifdef CONFIG_MEMCG
-DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+DECLARE_EVENT_CLASS(mm_vmscan_memcg_reclaim_end_template,
 
-	TP_ARGS(nr_reclaimed)
+	TP_PROTO(unsigned long nr_reclaimed, const struct mem_cgroup *memcg),
+
+	TP_ARGS(nr_reclaimed, memcg),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, nr_reclaimed)
+		__array(char, name, NAME_MAX + 1)
+	),
+
+	TP_fast_assign(
+		__entry->nr_reclaimed = nr_reclaimed;
+		cgroup_name(memcg->css.cgroup,
+			__entry->name,
+			sizeof(__entry->name));
+	),
+
+	TP_printk("nr_reclaimed=%lu memcg=%s",
+		__entry->nr_reclaimed,
+		__entry->name)
 );
 
-DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_softlimit_reclaim_end,
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_end_template, mm_vmscan_memcg_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, const struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(nr_reclaimed, memcg)
 );
+
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_end_template, mm_vmscan_memcg_softlimit_reclaim_end,
+
+	TP_PROTO(unsigned long nr_reclaimed, const struct mem_cgroup *memcg),
+
+	TP_ARGS(nr_reclaimed, memcg)
+);
+
 #endif /* CONFIG_MEMCG */
 
 TRACE_EVENT(mm_shrink_slab_start,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1080209a568b..45780952f4b5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7088,8 +7088,8 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 	sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
 			(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
 
-	trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
-						      sc.gfp_mask);
+	trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order, sc.gfp_mask,
+						      memcg);
 
 	/*
 	 * NOTE: Although we can get the priority field, using it
@@ -7100,7 +7100,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 	 */
 	shrink_lruvec(lruvec, &sc);
 
-	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
+	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed, memcg);
 
 	*nr_scanned = sc.nr_scanned;
 
@@ -7134,13 +7134,13 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 	struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
 
 	set_task_reclaim_state(current, &sc.reclaim_state);
-	trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask);
+	trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask, memcg);
 	noreclaim_flag = memalloc_noreclaim_save();
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
 	memalloc_noreclaim_restore(noreclaim_flag);
-	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
+	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed, memcg);
 	set_task_reclaim_state(current, NULL);
 
 	return nr_reclaimed;
-- 
2.36.0