[PATCH] mm/vmscan: expose cgroup_ino for memcg reclaim tracepoints

[Yafang Shao <laoar.shao@gmail.com>]

We can use the exposed cgroup_ino to trace specified cgroup.

For example,
step 1, get the inode of the specified cgroup
	$ ls -di /tmp/cgroupv2/foo
step 2, set this inode into tracepoint filter to trace this cgroup only
	(assume the inode is 11)
	$ cd /sys/kernel/debug/tracing/events/vmscan/
	$ echo 'cgroup_ino == 11' > mm_vmscan_memcg_reclaim_begin/filter
	$ echo 'cgroup_ino == 11' > mm_vmscan_memcg_reclaim_end/filter

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/trace/events/vmscan.h | 71 +++++++++++++++++++++++++++++++++++--------
 mm/vmscan.c                   | 18 ++++++++---
 2 files changed, 72 insertions(+), 17 deletions(-)

diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index c27a563..3be0023 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -133,18 +133,43 @@
 );
 
 #ifdef CONFIG_MEMCG
-DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
+DECLARE_EVENT_CLASS(mm_vmscan_memcg_reclaim_begin_template,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(unsigned int cgroup_ino, int order, gfp_t gfp_flags),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(cgroup_ino, order, gfp_flags),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, cgroup_ino)
+		__field(int, order)
+		__field(gfp_t, gfp_flags)
+	),
+
+	TP_fast_assign(
+		__entry->cgroup_ino	= cgroup_ino;
+		__entry->order		= order;
+		__entry->gfp_flags	= gfp_flags;
+	),
+
+	TP_printk("cgroup_ino=%u order=%d gfp_flags=%s",
+		__entry->cgroup_ino, __entry->order,
+		show_gfp_flags(__entry->gfp_flags))
 );
 
-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(unsigned int cgroup_ino, int order, gfp_t gfp_flags),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(cgroup_ino, order, gfp_flags)
+);
+
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_begin_template,
+	mm_vmscan_memcg_softlimit_reclaim_begin,
+
+	TP_PROTO(unsigned int cgroup_ino, int order, gfp_t gfp_flags),
+
+	TP_ARGS(cgroup_ino, order, gfp_flags)
 );
 #endif /* CONFIG_MEMCG */
 
@@ -173,18 +198,40 @@
 );
 
 #ifdef CONFIG_MEMCG
-DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_reclaim_end,
+DECLARE_EVENT_CLASS(mm_vmscan_memcg_reclaim_end_template,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned int cgroup_ino, unsigned long nr_reclaimed),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(cgroup_ino, nr_reclaimed),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, cgroup_ino)
+		__field(unsigned long, nr_reclaimed)
+	),
+
+	TP_fast_assign(
+		__entry->cgroup_ino	= cgroup_ino;
+		__entry->nr_reclaimed	= nr_reclaimed;
+	),
+
+	TP_printk("cgroup_ino=%u nr_reclaimed=%lu",
+		__entry->cgroup_ino, __entry->nr_reclaimed)
 );
 
-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 int cgroup_ino, unsigned long nr_reclaimed),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(cgroup_ino, nr_reclaimed)
+);
+
+DEFINE_EVENT(mm_vmscan_memcg_reclaim_end_template,
+	mm_vmscan_memcg_softlimit_reclaim_end,
+
+	TP_PROTO(unsigned int cgroup_ino, unsigned long nr_reclaimed),
+
+	TP_ARGS(cgroup_ino, nr_reclaimed)
 );
 #endif /* CONFIG_MEMCG */
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 347c9b3..15a9eb9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3268,8 +3268,10 @@ 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(
+				cgroup_ino(memcg->css.cgroup),
+				sc.order,
+				sc.gfp_mask);
 
 	/*
 	 * NOTE: Although we can get the priority field, using it
@@ -3280,7 +3282,9 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 	 */
 	shrink_node_memcg(pgdat, memcg, &sc);
 
-	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
+	trace_mm_vmscan_memcg_softlimit_reclaim_end(
+				cgroup_ino(memcg->css.cgroup),
+				sc.nr_reclaimed);
 
 	*nr_scanned = sc.nr_scanned;
 	return sc.nr_reclaimed;
@@ -3318,7 +3322,9 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 
 	zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK];
 
-	trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask);
+	trace_mm_vmscan_memcg_reclaim_begin(
+				cgroup_ino(memcg->css.cgroup),
+				0, sc.gfp_mask);
 
 	psi_memstall_enter(&pflags);
 	noreclaim_flag = memalloc_noreclaim_save();
@@ -3328,7 +3334,9 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 	memalloc_noreclaim_restore(noreclaim_flag);
 	psi_memstall_leave(&pflags);
 
-	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
+	trace_mm_vmscan_memcg_reclaim_end(
+				cgroup_ino(memcg->css.cgroup),
+				nr_reclaimed);
 
 	return nr_reclaimed;
 }
-- 
1.8.3.1