Re: [PATCH v2 10/18] mm, compaction: cleanup unused functions

[Michal Hocko <mhocko@kernel.org>]

On Tue 31-05-16 15:08:10, Vlastimil Babka wrote:
> Since kswapd compaction moved to kcompactd, compact_pgdat() is not called
> anymore, so we remove it. The only caller of __compact_pgdat() is
> compact_node(), so we merge them and remove code that was only reachable from
> kswapd.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/compaction.h |  5 ----
>  mm/compaction.c            | 60 +++++++++++++---------------------------------
>  2 files changed, 17 insertions(+), 48 deletions(-)
> 
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
> index b3bb66e7ce55..22a5fb9c509c 100644
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -70,7 +70,6 @@ extern int fragmentation_index(struct zone *zone, unsigned int order);
>  extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,
>  		unsigned int order, unsigned int alloc_flags,
>  		const struct alloc_context *ac, enum compact_priority prio);
> -extern void compact_pgdat(pg_data_t *pgdat, int order);
>  extern void reset_isolation_suitable(pg_data_t *pgdat);
>  extern enum compact_result compaction_suitable(struct zone *zone, int order,
>  		unsigned int alloc_flags, int classzone_idx);
> @@ -154,10 +153,6 @@ extern void kcompactd_stop(int nid);
>  extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx);
>  
>  #else
> -static inline void compact_pgdat(pg_data_t *pgdat, int order)
> -{
> -}
> -
>  static inline void reset_isolation_suitable(pg_data_t *pgdat)
>  {
>  }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 78c99300b911..af50f20de369 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1678,10 +1678,18 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
>  
>  
>  /* Compact all zones within a node */
> -static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
> +static void compact_node(int nid)
>  {
> +	pg_data_t *pgdat = NODE_DATA(nid);
>  	int zoneid;
>  	struct zone *zone;
> +	struct compact_control cc = {
> +		.order = -1,
> +		.mode = MIGRATE_SYNC,
> +		.ignore_skip_hint = true,
> +		.whole_zone = true,
> +	};
> +
>  
>  	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
>  
> @@ -1689,53 +1697,19 @@ static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
>  		if (!populated_zone(zone))
>  			continue;
>  
> -		cc->nr_freepages = 0;
> -		cc->nr_migratepages = 0;
> -		cc->zone = zone;
> -		INIT_LIST_HEAD(&cc->freepages);
> -		INIT_LIST_HEAD(&cc->migratepages);
> -
> -		if (is_via_compact_memory(cc->order) ||
> -				!compaction_deferred(zone, cc->order))
> -			compact_zone(zone, cc);
> -
> -		VM_BUG_ON(!list_empty(&cc->freepages));
> -		VM_BUG_ON(!list_empty(&cc->migratepages));
> +		cc.nr_freepages = 0;
> +		cc.nr_migratepages = 0;
> +		cc.zone = zone;
> +		INIT_LIST_HEAD(&cc.freepages);
> +		INIT_LIST_HEAD(&cc.migratepages);
>  
> -		if (is_via_compact_memory(cc->order))
> -			continue;
> +		compact_zone(zone, &cc);
>  
> -		if (zone_watermark_ok(zone, cc->order,
> -				low_wmark_pages(zone), 0, 0))
> -			compaction_defer_reset(zone, cc->order, false);
> +		VM_BUG_ON(!list_empty(&cc.freepages));
> +		VM_BUG_ON(!list_empty(&cc.migratepages));
>  	}
>  }
>  
> -void compact_pgdat(pg_data_t *pgdat, int order)
> -{
> -	struct compact_control cc = {
> -		.order = order,
> -		.mode = MIGRATE_ASYNC,
> -	};
> -
> -	if (!order)
> -		return;
> -
> -	__compact_pgdat(pgdat, &cc);
> -}
> -
> -static void compact_node(int nid)
> -{
> -	struct compact_control cc = {
> -		.order = -1,
> -		.mode = MIGRATE_SYNC,
> -		.ignore_skip_hint = true,
> -		.whole_zone = true,
> -	};
> -
> -	__compact_pgdat(NODE_DATA(nid), &cc);
> -}
> -
>  /* Compact all nodes in the system */
>  static void compact_nodes(void)
>  {
> -- 
> 2.8.3
> 
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-- 
Michal Hocko
SUSE Labs