linux-kernel - Re: [PATCHv2 4/6] zsmalloc: rework compaction algorithm

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Date:   Wed, 1 Mar 2023 12:47:03 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Yosry Ahmed <yosryahmed@...gle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv2 4/6] zsmalloc: rework compaction algorithm

On (23/02/28 15:14), Minchan Kim wrote:
> So, how about this on top of your patch?
> 

Looks good. Let me pick it up.

> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index eacf9e32da5c..4dfc910f5d89 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -2223,40 +2223,33 @@ static unsigned long __zs_compact(struct zs_pool *pool,
>  	 * as well as zpage allocation/free
>  	 */
>  	spin_lock(&pool->lock);
> -	while (1) {
> +	while (zs_can_compact(class)) {
> +		int ret;
> +
>  		if (!dst_zspage) {
>  			dst_zspage = isolate_dst_zspage(class);
>  			if (!dst_zspage)
> -				goto out;
> +				break;
>  			migrate_write_lock(dst_zspage);
>  			cc.d_page = get_first_page(dst_zspage);
>  		}
>  
> -		if (!zs_can_compact(class)) {
> -			putback_zspage(class, dst_zspage);
> -			migrate_write_unlock(dst_zspage);
> -			goto out;
> -		}
> -
>  		src_zspage = isolate_src_zspage(class);
> -		if (!src_zspage) {
> -			putback_zspage(class, dst_zspage);
> -			migrate_write_unlock(dst_zspage);
> -			goto out;
> -		}
> +		if (!src_zspage)
> +			break;
>  
>  		migrate_write_lock_nested(src_zspage);
> -
>  		cc.obj_idx = 0;
>  		cc.s_page = get_first_page(src_zspage);
> +
>  		migrate_zspage(pool, class, &cc);
> +		ret = putback_zspage(class, src_zspage);
> +		migrate_write_unlock(src_zspage);
>  
> -		if (putback_zspage(class, src_zspage) == ZS_INUSE_RATIO_0) {
> -			migrate_write_unlock(src_zspage);
> +		if (ret == ZS_INUSE_RATIO_0) {
>  			free_zspage(pool, class, src_zspage);
>  			pages_freed += class->pages_per_zspage;
> -		} else {
> -			migrate_write_unlock(src_zspage);
> +			src_zspage = NULL;
>  		}
>  
>  		if (get_fullness_group(class, dst_zspage) == ZS_INUSE_RATIO_100
> @@ -2264,14 +2257,22 @@ static unsigned long __zs_compact(struct zs_pool *pool,
>  			putback_zspage(class, dst_zspage);
>  			migrate_write_unlock(dst_zspage);
>  			dst_zspage = NULL;
> -		}
>  
> -		if (!dst_zspage) {
>  			spin_unlock(&pool->lock);
>  			cond_resched();
>  			spin_lock(&pool->lock);
>  		}
>  	}
> +
> +	if (src_zspage) {
> +		putback_zspage(class, src_zspage);
> +		migrate_write_unlock(src_zspage);
> +	}
> +
> +	if (dst_zspage) {
> +		putback_zspage(class, dst_zspage);
> +		migrate_write_unlock(dst_zspage);
> +	}
>  out:
>  	spin_unlock(&pool->lock);
>