[PATCH v4 7/9] mm/vmscan: pass scan_control to mm_vmscan_balance_pgdat_end

[Ridong Chen <ridong.chen@linux.dev>]

From: Ridong Chen <chenridong@xiaomi.com>

balance_pgdat() passes sc.order and sc.nr_reclaimed to
mm_vmscan_balance_pgdat_end as bare arguments. Pass the enclosing
struct scan_control instead and read the fields out in TP_fast_assign,
consistent with the other reclaim tracepoints. 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).

Assisted-by: LLM
Signed-off-by: Ridong Chen <chenridong@xiaomi.com>
---
 mm/trace_vmscan.h | 9 ++++-----
 mm/vmscan.c       | 3 +--
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/mm/trace_vmscan.h b/mm/trace_vmscan.h
index 54168ad45f6e..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",
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4bb00371a67f..5d699decaa28 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7402,8 +7402,7 @@ 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
-- 
2.34.1