Re: [PATCHv1 2/6] zsmalloc: factor out size-class locking helpers

[Yosry Ahmed <yosry.ahmed@linux.dev>]

On Wed, Jan 29, 2025 at 03:43:48PM +0900, Sergey Senozhatsky wrote:
> Move open-coded size-class locking to dedicated helpers.
> 
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>

Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>

> ---
>  mm/zsmalloc.c | 47 ++++++++++++++++++++++++++++-------------------
>  1 file changed, 28 insertions(+), 19 deletions(-)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 2f8a2b139919..0f575307675d 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -254,6 +254,16 @@ static bool pool_lock_is_contended(struct zs_pool *pool)
>  	return rwlock_is_contended(&pool->migrate_lock);
>  }
>  
> +static void size_class_lock(struct size_class *class)
> +{
> +	spin_lock(&class->lock);
> +}
> +
> +static void size_class_unlock(struct size_class *class)
> +{
> +	spin_unlock(&class->lock);
> +}
> +
>  static inline void zpdesc_set_first(struct zpdesc *zpdesc)
>  {
>  	SetPagePrivate(zpdesc_page(zpdesc));
> @@ -614,8 +624,7 @@ static int zs_stats_size_show(struct seq_file *s, void *v)
>  		if (class->index != i)
>  			continue;
>  
> -		spin_lock(&class->lock);
> -
> +		size_class_lock(class);
>  		seq_printf(s, " %5u %5u ", i, class->size);
>  		for (fg = ZS_INUSE_RATIO_10; fg < NR_FULLNESS_GROUPS; fg++) {
>  			inuse_totals[fg] += class_stat_read(class, fg);
> @@ -625,7 +634,7 @@ static int zs_stats_size_show(struct seq_file *s, void *v)
>  		obj_allocated = class_stat_read(class, ZS_OBJS_ALLOCATED);
>  		obj_used = class_stat_read(class, ZS_OBJS_INUSE);
>  		freeable = zs_can_compact(class);
> -		spin_unlock(&class->lock);
> +		size_class_unlock(class);
>  
>  		objs_per_zspage = class->objs_per_zspage;
>  		pages_used = obj_allocated / objs_per_zspage *
> @@ -1400,7 +1409,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
>  	class = pool->size_class[get_size_class_index(size)];
>  
>  	/* class->lock effectively protects the zpage migration */
> -	spin_lock(&class->lock);
> +	size_class_lock(class);
>  	zspage = find_get_zspage(class);
>  	if (likely(zspage)) {
>  		obj_malloc(pool, zspage, handle);
> @@ -1411,7 +1420,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
>  		goto out;
>  	}
>  
> -	spin_unlock(&class->lock);
> +	size_class_unlock(class);
>  
>  	zspage = alloc_zspage(pool, class, gfp);
>  	if (!zspage) {
> @@ -1419,7 +1428,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
>  		return (unsigned long)ERR_PTR(-ENOMEM);
>  	}
>  
> -	spin_lock(&class->lock);
> +	size_class_lock(class);
>  	obj_malloc(pool, zspage, handle);
>  	newfg = get_fullness_group(class, zspage);
>  	insert_zspage(class, zspage, newfg);
> @@ -1430,7 +1439,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
>  	/* We completely set up zspage so mark them as movable */
>  	SetZsPageMovable(pool, zspage);
>  out:
> -	spin_unlock(&class->lock);
> +	size_class_unlock(class);
>  
>  	return handle;
>  }
> @@ -1484,7 +1493,7 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
>  	obj_to_zpdesc(obj, &f_zpdesc);
>  	zspage = get_zspage(f_zpdesc);
>  	class = zspage_class(pool, zspage);
> -	spin_lock(&class->lock);
> +	size_class_lock(class);
>  	pool_read_unlock(pool);
>  
>  	class_stat_sub(class, ZS_OBJS_INUSE, 1);
> @@ -1494,7 +1503,7 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
>  	if (fullness == ZS_INUSE_RATIO_0)
>  		free_zspage(pool, class, zspage);
>  
> -	spin_unlock(&class->lock);
> +	size_class_unlock(class);
>  	cache_free_handle(pool, handle);
>  }
>  EXPORT_SYMBOL_GPL(zs_free);
> @@ -1828,7 +1837,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
>  	/*
>  	 * the class lock protects zpage alloc/free in the zspage.
>  	 */
> -	spin_lock(&class->lock);
> +	size_class_lock(class);
>  	/* the migrate_write_lock protects zpage access via zs_map_object */
>  	migrate_write_lock(zspage);
>  
> @@ -1860,7 +1869,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
>  	 * it's okay to release migration_lock.
>  	 */
>  	pool_write_unlock(pool);
> -	spin_unlock(&class->lock);
> +	size_class_unlock(class);
>  	migrate_write_unlock(zspage);
>  
>  	zpdesc_get(newzpdesc);
> @@ -1904,10 +1913,10 @@ static void async_free_zspage(struct work_struct *work)
>  		if (class->index != i)
>  			continue;
>  
> -		spin_lock(&class->lock);
> +		size_class_lock(class);
>  		list_splice_init(&class->fullness_list[ZS_INUSE_RATIO_0],
>  				 &free_pages);
> -		spin_unlock(&class->lock);
> +		size_class_unlock(class);
>  	}
>  
>  	list_for_each_entry_safe(zspage, tmp, &free_pages, list) {
> @@ -1915,10 +1924,10 @@ static void async_free_zspage(struct work_struct *work)
>  		lock_zspage(zspage);
>  
>  		class = zspage_class(pool, zspage);
> -		spin_lock(&class->lock);
> +		size_class_lock(class);
>  		class_stat_sub(class, ZS_INUSE_RATIO_0, 1);
>  		__free_zspage(pool, class, zspage);
> -		spin_unlock(&class->lock);
> +		size_class_unlock(class);
>  	}
>  };
>  
> @@ -1983,7 +1992,7 @@ static unsigned long __zs_compact(struct zs_pool *pool,
>  	 * as well as zpage allocation/free
>  	 */
>  	pool_write_lock(pool);
> -	spin_lock(&class->lock);
> +	size_class_lock(class);
>  	while (zs_can_compact(class)) {
>  		int fg;
>  
> @@ -2013,11 +2022,11 @@ static unsigned long __zs_compact(struct zs_pool *pool,
>  			putback_zspage(class, dst_zspage);
>  			dst_zspage = NULL;
>  
> -			spin_unlock(&class->lock);
> +			size_class_unlock(class);
>  			pool_write_unlock(pool);
>  			cond_resched();
>  			pool_write_lock(pool);
> -			spin_lock(&class->lock);
> +			size_class_lock(class);
>  		}
>  	}
>  
> @@ -2027,7 +2036,7 @@ static unsigned long __zs_compact(struct zs_pool *pool,
>  	if (dst_zspage)
>  		putback_zspage(class, dst_zspage);
>  
> -	spin_unlock(&class->lock);
> +	size_class_unlock(class);
>  	pool_write_unlock(pool);
>  
>  	return pages_freed;
> -- 
> 2.48.1.262.g85cc9f2d1e-goog
>