Re: [PATCH v5 4/6] mm/vmscan: pass scan_control to the vmscan tracepoints

From: Baoquan He <baoquan.he@linux.dev>
Date: 2026-11-02 01:40:45
Also in: bpf, cgroups, linux-mm, lkml
Reply to: Ridong Chen, 2026-10-31

On 10/31/26 at 05:00pm, Ridong Chen wrote:

From: Ridong Chen <redacted>

Several vmscan tracepoints spell out reclaim state as individual
arguments, all of which the caller already holds in struct scan_control.
Now that the struct is visible from the trace header, pass sc directly
and pick the fields out in TP_fast_assign instead of spelling them out
at every callsite:

- mm_vmscan_direct_reclaim_begin, mm_vmscan_memcg_reclaim_begin and
  mm_vmscan_node_reclaim_begin: gfp_mask and order.

- mm_vmscan_lru_isolate, mm_vmscan_lru_shrink_inactive and
  mm_vmscan_lru_shrink_active: reclaim_idx, order and priority.

- mm_vmscan_reclaim_pages: nr_scanned. nr_reclaimed stays a separate
  argument: it is the return value of shrink_folio_list(), which does
  not update sc->nr_reclaimed.

- mm_vmscan_balance_pgdat_end: order and nr_reclaimed. highest_zoneidx
  stays a separate argument: it is a balance_pgdat() parameter, and
  sc.reclaim_idx may differ from it by the time the end event fires.

No functional change. The tracefs event format (TP_STRUCT__entry and
TP_printk) is unchanged, so tracefs-based consumers are unaffected.
BPF programs attached via raw_tp/tp_btf see the new TP_PROTO and need
to be adjusted; tracepoints are not a stable ABI (see
Documentation/bpf/bpf_design_QA.rst).

Signed-off-by: Ridong Chen <redacted>
---
 mm/trace_vmscan.h | 74 +++++++++++++++++++++++------------------------
 mm/vmscan.c       | 26 ++++++++---------
 2 files changed, 48 insertions(+), 52 deletions(-)

LGMT,

Reviewed-by: Baoquan He <baoquan.he@linux.dev>

quoted hunk ↗ jump to hunk

diff --git a/mm/trace_vmscan.h b/mm/trace_vmscan.h
index 3917e1b62dfa..b2ad83e5f25e 100644
--- a/mm/trace_vmscan.h
+++ b/mm/trace_vmscan.h

@@ -124,10 +124,9 @@ TRACE_EVENT(mm_vmscan_balance_pgdat_begin,
 
 TRACE_EVENT(mm_vmscan_balance_pgdat_end,
 
-	TP_PROTO(int nid, int order, int highest_zoneidx,
-		 unsigned long nr_reclaimed),
+	TP_PROTO(int nid, struct scan_control *sc, int highest_zoneidx),
 
-	TP_ARGS(nid, order, highest_zoneidx, nr_reclaimed),
+	TP_ARGS(nid, sc, highest_zoneidx),
 
 	TP_STRUCT__entry(
 		__field(int, nid)

@@ -138,9 +137,9 @@ TRACE_EVENT(mm_vmscan_balance_pgdat_end,
 
 	TP_fast_assign(
 		__entry->nid = nid;
-		__entry->order = order;
+		__entry->order = sc->order;
 		__entry->highest_zoneidx = highest_zoneidx;
-		__entry->nr_reclaimed = nr_reclaimed;
+		__entry->nr_reclaimed = sc->nr_reclaimed;
 	),
 
 	TP_printk("nid=%d order=%d highest_zoneidx=%-8s nr_reclaimed=%lu",

@@ -178,9 +177,9 @@ TRACE_EVENT(mm_vmscan_wakeup_kswapd,
 
 DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
 
-	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
+	TP_PROTO(struct scan_control *sc, struct mem_cgroup *memcg),
 
-	TP_ARGS(gfp_flags, order, memcg),
+	TP_ARGS(sc, memcg),
 
 	TP_STRUCT__entry(
 		__field(	unsigned long,	gfp_flags	)

@@ -189,8 +188,8 @@ DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
 	),
 
 	TP_fast_assign(
-		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
-		__entry->order		= order;
+		__entry->gfp_flags	= (__force unsigned long)sc->gfp_mask;
+		__entry->order		= sc->order;
 		__entry->memcg_id	= mem_cgroup_id(memcg);
 	),

@@ -204,17 +203,17 @@ DECLARE_EVENT_CLASS(mm_vmscan_direct_reclaim_begin_template,
 
 DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_direct_reclaim_begin,
 
-	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
+	TP_PROTO(struct scan_control *sc, struct mem_cgroup *memcg),
 
-	TP_ARGS(gfp_flags, order, memcg)
+	TP_ARGS(sc, memcg)
 );
 
 #ifdef CONFIG_MEMCG
 DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,
 
-	TP_PROTO(gfp_t gfp_flags, int order, struct mem_cgroup *memcg),
+	TP_PROTO(struct scan_control *sc, struct mem_cgroup *memcg),
 
-	TP_ARGS(gfp_flags, order, memcg)
+	TP_ARGS(sc, memcg)
 );
 #endif /* CONFIG_MEMCG */

@@ -350,15 +349,14 @@ TRACE_EVENT(mm_shrink_slab_end,
 );
 
 TRACE_EVENT(mm_vmscan_lru_isolate,
-	TP_PROTO(int highest_zoneidx,
-		int order,
-		unsigned long nr_requested,
-		unsigned long nr_scanned,
-		unsigned long nr_skipped,
-		unsigned long nr_taken,
-		int lru),
+	TP_PROTO(struct scan_control *sc,
+		 unsigned long nr_requested,
+		 unsigned long nr_scanned,
+		 unsigned long nr_skipped,
+		 unsigned long nr_taken,
+		 int lru),
 
-	TP_ARGS(highest_zoneidx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, lru),
+	TP_ARGS(sc, nr_requested, nr_scanned, nr_skipped, nr_taken, lru),
 
 	TP_STRUCT__entry(
 		__field(int, highest_zoneidx)

@@ -371,8 +369,8 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
 	),
 
 	TP_fast_assign(
-		__entry->highest_zoneidx = highest_zoneidx;
-		__entry->order = order;
+		__entry->highest_zoneidx = sc->reclaim_idx;
+		__entry->order = sc->order;
 		__entry->nr_requested = nr_requested;
 		__entry->nr_scanned = nr_scanned;
 		__entry->nr_skipped = nr_skipped;

@@ -419,11 +417,11 @@ TRACE_EVENT(mm_vmscan_write_folio,
 
 TRACE_EVENT(mm_vmscan_reclaim_pages,
 
-	TP_PROTO(int nid,
-		unsigned long nr_scanned, unsigned long nr_reclaimed,
-		struct reclaim_stat *stat),
+	TP_PROTO(int nid, struct scan_control *sc,
+		 unsigned long nr_reclaimed,
+		 struct reclaim_stat *stat),
 
-	TP_ARGS(nid, nr_scanned, nr_reclaimed, stat),
+	TP_ARGS(nid, sc, nr_reclaimed, stat),
 
 	TP_STRUCT__entry(
 		__field(int, nid)

@@ -441,7 +439,7 @@ TRACE_EVENT(mm_vmscan_reclaim_pages,
 
 	TP_fast_assign(
 		__entry->nid = nid;
-		__entry->nr_scanned = nr_scanned;
+		__entry->nr_scanned = sc->nr_scanned;
 		__entry->nr_reclaimed = nr_reclaimed;
 		__entry->nr_dirty = stat->nr_dirty;
 		__entry->nr_writeback = stat->nr_writeback;

@@ -466,9 +464,9 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive,
 
 	TP_PROTO(int nid,
 		unsigned long nr_scanned, unsigned long nr_reclaimed,
-		struct reclaim_stat *stat, int priority, int file),
+		struct reclaim_stat *stat, struct scan_control *sc, int file),
 
-	TP_ARGS(nid, nr_scanned, nr_reclaimed, stat, priority, file),
+	TP_ARGS(nid, nr_scanned, nr_reclaimed, stat, sc, file),
 
 	TP_STRUCT__entry(
 		__field(int, nid)

@@ -498,7 +496,7 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive,
 		__entry->nr_activate1 = stat->nr_activate[1];
 		__entry->nr_ref_keep = stat->nr_ref_keep;
 		__entry->nr_unmap_fail = stat->nr_unmap_fail;
-		__entry->priority = priority;
+		__entry->priority = sc->priority;
 		__entry->reclaim_flags = trace_reclaim_flags(file);
 	),

@@ -517,9 +515,9 @@ TRACE_EVENT(mm_vmscan_lru_shrink_active,
 
 	TP_PROTO(int nid, unsigned long nr_taken,
 		unsigned long nr_active, unsigned long nr_deactivated,
-		unsigned long nr_referenced, int priority, int file),
+		unsigned long nr_referenced, struct scan_control *sc, int file),
 
-	TP_ARGS(nid, nr_taken, nr_active, nr_deactivated, nr_referenced, priority, file),
+	TP_ARGS(nid, nr_taken, nr_active, nr_deactivated, nr_referenced, sc, file),
 
 	TP_STRUCT__entry(
 		__field(int, nid)

@@ -537,7 +535,7 @@ TRACE_EVENT(mm_vmscan_lru_shrink_active,
 		__entry->nr_active = nr_active;
 		__entry->nr_deactivated = nr_deactivated;
 		__entry->nr_referenced = nr_referenced;
-		__entry->priority = priority;
+		__entry->priority = sc->priority;
 		__entry->reclaim_flags = trace_reclaim_flags(file);
 	),

@@ -551,9 +549,9 @@ TRACE_EVENT(mm_vmscan_lru_shrink_active,
 
 TRACE_EVENT(mm_vmscan_node_reclaim_begin,
 
-	TP_PROTO(int nid, int order, gfp_t gfp_flags),
+	TP_PROTO(int nid, struct scan_control *sc),
 
-	TP_ARGS(nid, order, gfp_flags),
+	TP_ARGS(nid, sc),
 
 	TP_STRUCT__entry(
 		__field(int, nid)

@@ -563,8 +561,8 @@ TRACE_EVENT(mm_vmscan_node_reclaim_begin,
 
 	TP_fast_assign(
 		__entry->nid = nid;
-		__entry->order = order;
-		__entry->gfp_flags = (__force unsigned long)gfp_flags;
+		__entry->order = sc->order;
+		__entry->gfp_flags = (__force unsigned long)sc->gfp_mask;
 	),
 
 	TP_printk("nid=%d order=%d gfp_flags=%s",

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 49677464fc9a..15e9184a580a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -1764,7 +1764,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
 		}
 	}
 	*nr_scanned = total_scan;
-	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
+	trace_mm_vmscan_lru_isolate(sc, nr_to_scan,
 				    total_scan, skipped, nr_taken, lru);
 	update_lru_sizes(lruvec, lru, nr_zone_taken);
 	return nr_taken;

@@ -2053,7 +2053,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
 
 	handle_reclaim_writeback(nr_taken, pgdat, sc, &stat);
 	trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
-			nr_scanned, nr_reclaimed, &stat, sc->priority, file);
+			nr_scanned, nr_reclaimed, &stat, sc, file);
 	return nr_reclaimed;
 }

@@ -2160,7 +2160,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 		mod_lruvec_state(lruvec, PGROTATE_ANON + file, nr_rotated);
 
 	trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
-			nr_deactivate, nr_rotated, sc->priority, file);
+			nr_deactivate, nr_rotated, sc, file);
 }
 
 static unsigned int reclaim_folio_list(struct list_head *folio_list,

@@ -2183,7 +2183,7 @@ static unsigned int reclaim_folio_list(struct list_head *folio_list,
 		list_del(&folio->lru);
 		folio_putback_lru(folio);
 	}
-	trace_mm_vmscan_reclaim_pages(pgdat->node_id, sc.nr_scanned, nr_reclaimed, &stat);
+	trace_mm_vmscan_reclaim_pages(pgdat->node_id, &sc, nr_reclaimed, &stat);
 
 	return nr_reclaimed;
 }

@@ -4849,9 +4849,9 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	mod_lruvec_state(lruvec, item, isolated);
 	mod_lruvec_state(lruvec, PGREFILL, sorted);
 	mod_lruvec_state(lruvec, PGSCAN_ANON + type, isolated);
-	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
-				scanned, skipped, isolated,
-				type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
+	trace_mm_vmscan_lru_isolate(sc, nr_to_scan,
+				    scanned, skipped, isolated,
+				    type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
 
 	*isolatedp = isolated;
 	return scanned;

@@ -4993,7 +4993,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	if (isolated)
 		handle_reclaim_writeback(isolated, pgdat, sc, &stat);
 	trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
-			type_scanned, reclaimed, &stat, sc->priority,
+			type_scanned, reclaimed, &stat, sc,
 			type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
 
 	list_for_each_entry_safe_reverse(folio, next, &list, lru) {

@@ -6889,7 +6889,7 @@ 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(sc.gfp_mask, order, NULL);
+	trace_mm_vmscan_direct_reclaim_begin(&sc, NULL);
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);

@@ -6930,7 +6930,7 @@ 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(sc.gfp_mask, 0, memcg);
+	trace_mm_vmscan_memcg_reclaim_begin(&sc, memcg);
 	noreclaim_flag = memalloc_noreclaim_save();
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);

@@ -7407,8 +7407,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
 	psi_memstall_leave(&pflags);
 	set_task_reclaim_state(current, NULL);
 
-	trace_mm_vmscan_balance_pgdat_end(pgdat->node_id, sc.order,
-					  highest_zoneidx, sc.nr_reclaimed);
+	trace_mm_vmscan_balance_pgdat_end(pgdat->node_id, &sc, highest_zoneidx);
 
 	/*
 	 * Return the order kswapd stopped reclaiming at as

@@ -7886,8 +7885,7 @@ static unsigned long __node_reclaim(struct pglist_data *pgdat,
 	unsigned int noreclaim_flag;
 	unsigned long pflags;
 
-	trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, sc->order,
-					   sc->gfp_mask);
+	trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, sc);
 
 	cond_resched();
 	if (!sc->proactive)

-- 
2.43.0

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