[PATCH v8 2/3] mm: vmscan: add cgroup IDs to vmscan tracepoints

STALE207d

From: Thomas Ballasi <hidden>
Date: 2026-03-16 16:09:29
Also in: linux-mm
Subsystem: memory management, memory management - mglru (multi-gen lru), memory management - reclaim, shrinker, the rest, tracing · Maintainers: Andrew Morton, Johannes Weiner, Dave Chinner, Linus Torvalds, Steven Rostedt, Masami Hiramatsu

Revision v8 of 8 in this series.

Revisions (8)

2025-12-08 v1 [diff vs current]
2025-12-16 v2 [diff vs current]
2026-01-05 v3 [diff vs current]
2026-01-15 v4 [diff vs current]
2026-01-22 v5 [diff vs current]
2026-02-13 v6 [diff vs current]
2026-02-23 v7 [diff vs current]
2026-03-16 v8 current

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..1212f6a7c223e 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, struct mem_cgroup *memcg),
 
-	TP_ARGS(order, gfp_flags),
+	TP_ARGS(gfp_flags, order, memcg),
 
 	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	= mem_cgroup_id(memcg);
 	),
 
-	TP_printk("order=%d gfp_flags=%s",
+	TP_printk("order=%d gfp_flags=%s memcg_id=%llu",
 		__entry->order,
-		show_gfp_flags(__entry->gfp_flags))
+		show_gfp_flags(__entry->gfp_flags),
+		__entry->memcg_id)
 );
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_direct_reclaim_begin,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(gfp_flags, order, memcg)
 );
 
 #ifdef CONFIG_MEMCG
 DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(gfp_flags, order, memcg)
 );
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_softlimit_reclaim_begin,
 
-	TP_PROTO(int order, gfp_t gfp_flags),
+	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
 
-	TP_ARGS(order, gfp_flags)
+	TP_ARGS(gfp_flags, order, memcg)
 );
 #endif /* CONFIG_MEMCG */
 
 DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_end_template,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed),
+	TP_ARGS(nr_reclaimed, memcg),
 
 	TP_STRUCT__entry(
 		__field(	unsigned long,	nr_reclaimed	)
+		__field(	u64,	memcg_id	)
 	),
 
 	TP_fast_assign(
 		__entry->nr_reclaimed	= nr_reclaimed;
+		__entry->memcg_id	= mem_cgroup_id(memcg);
 	),
 
-	TP_printk("nr_reclaimed=%lu", __entry->nr_reclaimed)
+	TP_printk("nr_reclaimed=%lu memcg_id=%llu",
+		__entry->nr_reclaimed,
+		__entry->memcg_id)
 );
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_direct_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(nr_reclaimed, memcg)
 );
 
 #ifdef CONFIG_MEMCG
 DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(nr_reclaimed, memcg)
 );
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_softlimit_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(nr_reclaimed, memcg)
 );
 #endif /* CONFIG_MEMCG */

@@ -200,39 +207,42 @@ TRACE_EVENT(mm_shrink_slab_start,
 	TP_PROTO(struct shrinker *shr, struct shrink_control *sc,
 		long nr_objects_to_shrink, unsigned long cache_items,
 		unsigned long long delta, unsigned long total_scan,
-		int priority),
+		int priority, struct mem_cgroup *memcg),
 
 	TP_ARGS(shr, sc, nr_objects_to_shrink, cache_items, delta, total_scan,
-		priority),
+		priority, memcg),
 
 	TP_STRUCT__entry(
 		__field(struct shrinker *, shr)
 		__field(void *, shrink)
-		__field(int, nid)
 		__field(long, nr_objects_to_shrink)
 		__field(unsigned long, gfp_flags)
 		__field(unsigned long, cache_items)
 		__field(unsigned long long, delta)
 		__field(unsigned long, total_scan)
 		__field(int, priority)
+		__field(int, nid)
+		__field(u64, memcg_id)
 	),
 
 	TP_fast_assign(
 		__entry->shr = shr;
 		__entry->shrink = shr->scan_objects;
-		__entry->nid = sc->nid;
 		__entry->nr_objects_to_shrink = nr_objects_to_shrink;
 		__entry->gfp_flags = (__force unsigned long)sc->gfp_mask;
 		__entry->cache_items = cache_items;
 		__entry->delta = delta;
 		__entry->total_scan = total_scan;
 		__entry->priority = priority;
+		__entry->nid = sc->nid;
+		__entry->memcg_id = mem_cgroup_id(memcg);
 	),
 
-	TP_printk("%pS %p: nid: %d objects to shrink %ld gfp_flags %s cache items %ld delta %lld total_scan %ld priority %d",
+	TP_printk("%pS %p: nid: %d memcg_id: %llu objects to shrink %ld gfp_flags %s cache items %ld delta %lld total_scan %ld priority %d",
 		__entry->shrink,
 		__entry->shr,
 		__entry->nid,
+		__entry->memcg_id,
 		__entry->nr_objects_to_shrink,
 		show_gfp_flags(__entry->gfp_flags),
 		__entry->cache_items,

@@ -243,35 +253,38 @@ TRACE_EVENT(mm_shrink_slab_start,
 
 TRACE_EVENT(mm_shrink_slab_end,
 	TP_PROTO(struct shrinker *shr, int nid, int shrinker_retval,
-		long unused_scan_cnt, long new_scan_cnt, long total_scan),
+		long unused_scan_cnt, long new_scan_cnt, long total_scan, struct mem_cgroup *memcg),
 
 	TP_ARGS(shr, nid, shrinker_retval, unused_scan_cnt, new_scan_cnt,
-		total_scan),
+		total_scan, memcg),
 
 	TP_STRUCT__entry(
 		__field(struct shrinker *, shr)
-		__field(int, nid)
 		__field(void *, shrink)
 		__field(long, unused_scan)
 		__field(long, new_scan)
-		__field(int, retval)
 		__field(long, total_scan)
+		__field(int, nid)
+		__field(int, retval)
+		__field(u64, memcg_id)
 	),
 
 	TP_fast_assign(
 		__entry->shr = shr;
-		__entry->nid = nid;
 		__entry->shrink = shr->scan_objects;
 		__entry->unused_scan = unused_scan_cnt;
 		__entry->new_scan = new_scan_cnt;
-		__entry->retval = shrinker_retval;
 		__entry->total_scan = total_scan;
+		__entry->nid = nid;
+		__entry->retval = shrinker_retval;
+		__entry->memcg_id = mem_cgroup_id(memcg);
 	),
 
-	TP_printk("%pS %p: nid: %d unused scan count %ld new scan count %ld total_scan %ld last shrinker return val %d",
+	TP_printk("%pS %p: nid: %d memcg_id: %llu unused scan count %ld new scan count %ld total_scan %ld last shrinker return val %d",
 		__entry->shrink,
 		__entry->shr,
 		__entry->nid,
+		__entry->memcg_id,
 		__entry->unused_scan,
 		__entry->new_scan,
 		__entry->total_scan,

@@ -504,9 +517,9 @@ TRACE_EVENT(mm_vmscan_node_reclaim_begin,
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_node_reclaim_end,
 
-	TP_PROTO(unsigned long nr_reclaimed),
+	TP_PROTO(unsigned long nr_reclaimed, struct mem_cgroup *memcg),
 
-	TP_ARGS(nr_reclaimed)
+	TP_ARGS(nr_reclaimed, memcg)
 );
 
 TRACE_EVENT(mm_vmscan_throttled,

diff --git a/mm/shrinker.c b/mm/shrinker.c
index 4a93fd433689a..ddf784f996a59 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c

@@ -410,7 +410,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 	total_scan = min(total_scan, (2 * freeable));
 
 	trace_mm_shrink_slab_start(shrinker, shrinkctl, nr,
-				   freeable, delta, total_scan, priority);
+				   freeable, delta, total_scan, priority,
+				   shrinkctl->memcg);
 
 	/*
 	 * Normally, we should not scan less than batch_size objects in one

@@ -461,7 +462,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 	 */
 	new_nr = add_nr_deferred(next_deferred, shrinker, shrinkctl);
 
-	trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan);
+	trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan,
+				 shrinkctl->memcg);
 	return freed;
 }

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 05d9354a59c65..b3117814ec436 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -6652,11 +6652,11 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 		return 1;
 
 	set_task_reclaim_state(current, &sc.reclaim_state);
-	trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
+	trace_mm_vmscan_direct_reclaim_begin(sc.gfp_mask, order, 0);
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
-	trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
+	trace_mm_vmscan_direct_reclaim_end(nr_reclaimed, 0);
 	set_task_reclaim_state(current, NULL);
 
 	return nr_reclaimed;

@@ -6685,8 +6685,9 @@ 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.gfp_mask,
+						      sc.order,
+						      memcg);
 
 	/*
 	 * NOTE: Although we can get the priority field, using it

@@ -6697,7 +6698,7 @@ 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;

@@ -6733,13 +6734,13 @@ 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(sc.gfp_mask, 0, 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;

@@ -7685,7 +7686,7 @@ static unsigned long __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask,
 	delayacct_freepages_end();
 	psi_memstall_leave(&pflags);
 
-	trace_mm_vmscan_node_reclaim_end(sc->nr_reclaimed);
+	trace_mm_vmscan_node_reclaim_end(sc->nr_reclaimed, 0);
 
 	return sc->nr_reclaimed;
 }

-- 
2.45.3

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