Re: [PATCH v2] mm: use zonelist_zone() to get zone

["Garg, Shivank" <shivankg@amd.com>]

On 7/9/2024 8:49 AM, Wei Yang wrote:
> Instead of accessing zoneref->zone directly, use zonelist_zone() like
> other places for consistency.
> 
> No functional change.
> 
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> CC: Mike Rapoport (IBM) <rppt@kernel.org>
> CC: David Hildenbrand <david@redhat.com>
> CC: Garg Shivank <shivankg@amd.com>
> 
> ---
> v2: cover more usage
> ---
>  include/linux/mmzone.h     |  4 ++--
>  include/trace/events/oom.h |  2 +-
>  mm/mempolicy.c             |  4 ++--
>  mm/page_alloc.c            | 14 +++++++-------
>  4 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index cb7f265c2b96..51bce636373f 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1690,7 +1690,7 @@ static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
>  			zone = zonelist_zone(z))
>  
>  #define for_next_zone_zonelist_nodemask(zone, z, highidx, nodemask) \
> -	for (zone = z->zone;	\
> +	for (zone = zonelist_zone(z);	\
>  		zone;							\
>  		z = next_zones_zonelist(++z, highidx, nodemask),	\
>  			zone = zonelist_zone(z))
> @@ -1726,7 +1726,7 @@ static inline bool movable_only_nodes(nodemask_t *nodes)
>  	nid = first_node(*nodes);
>  	zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK];
>  	z = first_zones_zonelist(zonelist, ZONE_NORMAL,	nodes);
> -	return (!z->zone) ? true : false;
> +	return (!zonelist_zone(z)) ? true : false;
>  }
>  
>  
> diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h
> index a42be4c8563b..fe6997886b77 100644
> --- a/include/trace/events/oom.h
> +++ b/include/trace/events/oom.h
> @@ -55,7 +55,7 @@ TRACE_EVENT(reclaim_retry_zone,
>  	),
>  
>  	TP_fast_assign(
> -		__entry->node = zone_to_nid(zoneref->zone);
> +		__entry->node = zone_to_nid(zonelist_zone(zoneref));
>  		__entry->zone_idx = zoneref->zone_idx;
>  		__entry->order = order;
>  		__entry->reclaimable = reclaimable;
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index f73acb01ad45..83e26ded6278 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1951,7 +1951,7 @@ unsigned int mempolicy_slab_node(void)
>  		zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
>  		z = first_zones_zonelist(zonelist, highest_zoneidx,
>  							&policy->nodes);
> -		return z->zone ? zone_to_nid(z->zone) : node;
> +		return zonelist_zone(z) ? zone_to_nid(zonelist_zone(z)) : node;
>  	}
>  	case MPOL_LOCAL:
>  		return node;
> @@ -2806,7 +2806,7 @@ int mpol_misplaced(struct folio *folio, struct vm_fault *vmf,
>  				node_zonelist(thisnid, GFP_HIGHUSER),
>  				gfp_zone(GFP_HIGHUSER),
>  				&pol->nodes);
> -		polnid = zone_to_nid(z->zone);
> +		polnid = zone_to_nid(zonelist_zone(z));
>  		break;
>  
>  	default:
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 116ee33fd1ce..e2933885bb19 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4218,7 +4218,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>  	 */
>  	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
>  					ac->highest_zoneidx, ac->nodemask);
> -	if (!ac->preferred_zoneref->zone)
> +	if (!zonelist_zone(ac->preferred_zoneref))
>  		goto nopage;
>  
>  	/*
> @@ -4230,7 +4230,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>  		struct zoneref *z = first_zones_zonelist(ac->zonelist,
>  					ac->highest_zoneidx,
>  					&cpuset_current_mems_allowed);
> -		if (!z->zone)
> +		if (!zonelist_zone(z))
>  			goto nopage;
>  	}
>  
> @@ -4587,8 +4587,8 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>  			continue;
>  		}
>  
> -		if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
> -		    zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
> +		if (nr_online_nodes > 1 && zone != zonelist_zone(ac.preferred_zoneref) &&
> +		    zone_to_nid(zone) != zone_to_nid(zonelist_zone(ac.preferred_zoneref))) {
>  			goto failed;
>  		}
>  
> @@ -4647,7 +4647,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>  	pcp_trylock_finish(UP_flags);
>  
>  	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
> -	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
> +	zone_statistics(zonelist_zone(ac.preferred_zoneref), zone, nr_account);
>  
>  out:
>  	return nr_populated;
> @@ -4705,7 +4705,7 @@ struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order,
>  	 * Forbid the first pass from falling back to types that fragment
>  	 * memory until all local zones are considered.
>  	 */
> -	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
> +	alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
>  
>  	/* First allocation attempt */
>  	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
> @@ -5310,7 +5310,7 @@ int local_memory_node(int node)
>  	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
>  				   gfp_zone(GFP_KERNEL),
>  				   NULL);
> -	return zone_to_nid(z->zone);
> +	return zone_to_nid(zonelist_zone(z));
>  }
>  #endif
>  

Hi Wei,

I identified some additional locations where using zonelist_zone
and its related functions (zonelist_node_idx and zonelist_zone_idx) would
improve code consistency.

If it's alright with you, please append below changes to the patch with my tags.

Co-Developed-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>

I have also tested this patch.

Thanks,
Shivank

---
 include/trace/events/oom.h |  4 ++--
 mm/mempolicy.c             |  4 ++--
 mm/mmzone.c                |  2 +-
 mm/page_alloc.c            | 12 ++++++------
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h
index fe6997886b77..9f0a5d1482c4 100644
--- a/include/trace/events/oom.h
+++ b/include/trace/events/oom.h
@@ -55,8 +55,8 @@ TRACE_EVENT(reclaim_retry_zone,
 	),
 
 	TP_fast_assign(
-		__entry->node = zone_to_nid(zonelist_zone(zoneref));
-		__entry->zone_idx = zoneref->zone_idx;
+		__entry->node = zonelist_node_idx(zoneref);
+		__entry->zone_idx = zonelist_zone_idx(zoneref);
 		__entry->order = order;
 		__entry->reclaimable = reclaimable;
 		__entry->available = available;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e000f19b3852..ec84a11df1cc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1953,7 +1953,7 @@ unsigned int mempolicy_slab_node(void)
 		zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
 		z = first_zones_zonelist(zonelist, highest_zoneidx,
 							&policy->nodes);
-		return zonelist_zone(z) ? zone_to_nid(zonelist_zone(z)) : node;
+		return zonelist_zone(z) ? zonelist_node_idx(z) : node;
 	}
 	case MPOL_LOCAL:
 		return node;
@@ -2802,7 +2802,7 @@ int mpol_misplaced(struct folio *folio, struct vm_fault *vmf,
 				node_zonelist(thisnid, GFP_HIGHUSER),
 				gfp_zone(GFP_HIGHUSER),
 				&pol->nodes);
-		polnid = zone_to_nid(zonelist_zone(z));
+		polnid = zonelist_node_idx(z);
 		break;
 
 	default:
diff --git a/mm/mmzone.c b/mm/mmzone.c
index c01896eca736..f9baa8882fbf 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -66,7 +66,7 @@ struct zoneref *__next_zones_zonelist(struct zoneref *z,
 			z++;
 	else
 		while (zonelist_zone_idx(z) > highest_zoneidx ||
-				(z->zone && !zref_in_nodemask(z, nodes)))
+				(zonelist_zone(z) && !zref_in_nodemask(z, nodes)))
 			z++;
 
 	return z;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d841905fa260..e998ff6cbbff 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3336,7 +3336,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 		}
 
 		if (no_fallback && nr_online_nodes > 1 &&
-		    zone != ac->preferred_zoneref->zone) {
+		    zone != zonelist_zone(ac->preferred_zoneref)) {
 			int local_nid;
 
 			/*
@@ -3344,7 +3344,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 			 * fragmenting fallbacks. Locality is more important
 			 * than fragmentation avoidance.
 			 */
-			local_nid = zone_to_nid(ac->preferred_zoneref->zone);
+			local_nid = zonelist_node_idx(ac->preferred_zoneref);
 			if (zone_to_nid(zone) != local_nid) {
 				alloc_flags &= ~ALLOC_NOFRAGMENT;
 				goto retry;
@@ -3397,7 +3397,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 				goto try_this_zone;
 
 			if (!node_reclaim_enabled() ||
-			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
+			    !zone_allows_reclaim(zonelist_zone(ac->preferred_zoneref), zone))
 				continue;
 
 			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
@@ -3419,7 +3419,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 		}
 
 try_this_zone:
-		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
+		page = rmqueue(zonelist_zone(ac->preferred_zoneref), zone, order,
 				gfp_mask, alloc_flags, ac->migratetype);
 		if (page) {
 			prep_new_page(page, order, gfp_mask, alloc_flags);
@@ -4560,7 +4560,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
 		}
 
 		if (nr_online_nodes > 1 && zone != zonelist_zone(ac.preferred_zoneref) &&
-		    zone_to_nid(zone) != zone_to_nid(zonelist_zone(ac.preferred_zoneref))) {
+		    zone_to_nid(zone) != zonelist_node_idx(ac.preferred_zoneref)) {
 			goto failed;
 		}
 
@@ -5282,7 +5282,7 @@ int local_memory_node(int node)
 	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
 				   gfp_zone(GFP_KERNEL),
 				   NULL);
-	return zone_to_nid(zonelist_zone(z));
+	return zonelist_node_idx(z);
 }
 #endif
 
-- 
2.43.0