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

[Baoquan He]

On 10/31/26 at 05:00pm, Ridong Chen wrote:
> From: Ridong Chen <chenridong@xxxxxxxxxx>
> 
> 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 <chenridong@xxxxxxxxxx>
> ---
>  mm/trace_vmscan.h | 74 +++++++++++++++++++++++------------------------
>  mm/vmscan.c       | 26 ++++++++---------
>  2 files changed, 48 insertions(+), 52 deletions(-)

LGMT,

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

> 
> 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
>