linux-kernel - Re: [PATCH] mm: swap: Use memset to fill the swap_map with SWAP_HAS

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Message-ID: <bd833f513d2a47daaa55099421bd4f7a@huawei.com>
Date:   Wed, 7 Oct 2020 02:49:53 +0000
From:   linmiaohe <linmiaohe@...wei.com>
To:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: swap: Use memset to fill the swap_map with
 SWAP_HAS_CACHE

Friendly ping.

> We could use helper memset to fill the swap_map with SWAP_HAS_CACHE instead of a direct loop here to simplify the code. Also we can remove the local variable i and map this way.
>
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  mm/swapfile.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c index 8feaab31a3a9..b0b629b24e3a 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -975,8 +975,7 @@ static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)  {
>  	unsigned long idx;
>  	struct swap_cluster_info *ci;
> -	unsigned long offset, i;
> -	unsigned char *map;
> +	unsigned long offset;
>  
>  	/*
>  	 * Should not even be attempting cluster allocations when huge @@ -996,9 +995,7 @@ static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
>  	alloc_cluster(si, idx);
>  	cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE);
>  
> -	map = si->swap_map + offset;
> -	for (i = 0; i < SWAPFILE_CLUSTER; i++)
> -		map[i] = SWAP_HAS_CACHE;
> +	memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER);
>  	unlock_cluster(ci);
>  	swap_range_alloc(si, offset, SWAPFILE_CLUSTER);
>  	*slot = swp_entry(si->type, offset);
> --
> 2.19.1
>