linux-kernel - Re: [PATCH 2/9] mm/compaction: call list_is_{first}/{last} more intuitively in move_freelist

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Message-ID: <26477981-5348-2da0-8bc8-c736d080a2f2@linux.alibaba.com>
Date:   Tue, 15 Aug 2023 15:49:09 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Kemeng Shi <shikemeng@...weicloud.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, david@...hat.com
Subject: Re: [PATCH 2/9] mm/compaction: call list_is_{first}/{last} more
 intuitively in move_freelist_{head}/{tail}



On 8/5/2023 7:07 PM, Kemeng Shi wrote:
> We use move_freelist_head after list_for_each_entry_reverse to skip
> recent pages. And there is no need to do actual move if all freepages
> are searched in list_for_each_entry_reverse, e.g. freepage point to
> first page in freelist. It's more intuitively to call list_is_first
> with list entry as the first argument and list head as the second
> argument to check if list entry is the first list entry instead of
> call list_is_last with list entry and list head passed in reverse.
> 
> Similarly, call list_is_last in move_freelist_tail is more intuitively.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Make sense to me.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

> ---
>   mm/compaction.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 513b1caeb4fa..fa1b100b0d10 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1395,7 +1395,7 @@ move_freelist_head(struct list_head *freelist, struct page *freepage)
>   {
>   	LIST_HEAD(sublist);
>   
> -	if (!list_is_last(freelist, &freepage->buddy_list)) {
> +	if (!list_is_first(&freepage->buddy_list, freelist)) {
>   		list_cut_before(&sublist, freelist, &freepage->buddy_list);
>   		list_splice_tail(&sublist, freelist);
>   	}
> @@ -1412,7 +1412,7 @@ move_freelist_tail(struct list_head *freelist, struct page *freepage)
>   {
>   	LIST_HEAD(sublist);
>   
> -	if (!list_is_first(freelist, &freepage->buddy_list)) {
> +	if (!list_is_last(&freepage->buddy_list, freelist)) {
>   		list_cut_position(&sublist, freelist, &freepage->buddy_list);
>   		list_splice_tail(&sublist, freelist);
>   	}