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

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

On 7/6/2024 7:20 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>
> ---
>  include/linux/mmzone.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 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;
>  }
>  
>  


Hi Wei,

I'd like to propose extending the use of the zonelist_zone helper
function in several other locations.

I've identified the following places where zonelist_zone could be
used instead of the current approach:

oom.h:58 __entry->node = zone_to_nid(zoneref->zone);
mempolicy.c:1956 return z->zone ? zone_to_nid(z->zone) : node;
mempolicy.c:2805 polnid = zone_to_nid(z->zone);
page_alloc.c:4205 if (!z->zone)
page_alloc.c:5285 return zone_to_nid(z->zone);

I hope this will further help with improving readability and
maintainability across mm.

Thanks,
Shivank