linux-kernel - Re: [PATCH 2/4] mm, swap: rename helper for setup bad slots

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Message-ID: <CACePvbXtWQq0g+K0YtQLi3Sz5ukS5YS3XF-_VDEmUR0Y3f_Agg@mail.gmail.com>
Date: Wed, 8 Oct 2025 13:58:45 -0700
From: Chris Li <chrisl@...nel.org>
To: Kairui Song <ryncsn@...il.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>, 
	Kemeng Shi <shikemeng@...weicloud.com>, Kairui Song <kasong@...cent.com>, 
	Nhat Pham <nphamcs@...il.com>, Baoquan He <bhe@...hat.com>, Barry Song <baohua@...nel.org>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, David Hildenbrand <david@...hat.com>, 
	"Matthew Wilcox (Oracle)" <willy@...radead.org>, Ying Huang <ying.huang@...ux.alibaba.com>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] mm, swap: rename helper for setup bad slots

Acked-by: Chris Li <chrisl@...nel.org>

Chris

On Mon, Oct 6, 2025 at 1:03 PM Kairui Song <ryncsn@...il.com> wrote:
>
> From: Kairui Song <kasong@...cent.com>
>
> The name inc_cluster_info_page is very confusing, as this helper is only
> used during swapon to mark bad slots. Rename it properly and turn the
> VM_BUG_ON in it into WARN_ON to expose more potential issues. Swapon is
> a cold path, so adding more checks should be a good idea.
>
> No feature change except new WARN_ON.
>
> Signed-off-by: Kairui Song <kasong@...cent.com>
> ---
>  mm/swapfile.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 0d1924f6f495..732e07c70ce9 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -751,14 +751,14 @@ static void relocate_cluster(struct swap_info_struct *si,
>  }
>
>  /*
> - * The cluster corresponding to page_nr will be used. The cluster will not be
> - * added to free cluster list and its usage counter will be increased by 1.
> - * Only used for initialization.
> + * The cluster corresponding to @offset will be accounted as having one bad
> + * slot. The cluster will not be added to the free cluster list, and its
> + * usage counter will be increased by 1. Only used for initialization.
>   */
> -static int inc_cluster_info_page(struct swap_info_struct *si,
> -       struct swap_cluster_info *cluster_info, unsigned long page_nr)
> +static int swap_cluster_setup_bad_slot(struct swap_cluster_info *cluster_info,
> +                                      unsigned long offset)
>  {
> -       unsigned long idx = page_nr / SWAPFILE_CLUSTER;
> +       unsigned long idx = offset / SWAPFILE_CLUSTER;
>         struct swap_table *table;
>         struct swap_cluster_info *ci;
>
> @@ -772,8 +772,8 @@ static int inc_cluster_info_page(struct swap_info_struct *si,
>
>         ci->count++;
>
> -       VM_BUG_ON(ci->count > SWAPFILE_CLUSTER);
> -       VM_BUG_ON(ci->flags);
> +       WARN_ON(ci->count > SWAPFILE_CLUSTER);
> +       WARN_ON(ci->flags);
>
>         return 0;
>  }
> @@ -3396,7 +3396,7 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
>          * See setup_swap_map(): header page, bad pages,
>          * and the EOF part of the last cluster.
>          */
> -       err = inc_cluster_info_page(si, cluster_info, 0);
> +       err = swap_cluster_setup_bad_slot(cluster_info, 0);
>         if (err)
>                 goto err;
>         for (i = 0; i < swap_header->info.nr_badpages; i++) {
> @@ -3404,12 +3404,12 @@ static struct swap_cluster_info *setup_clusters(struct swap_info_struct *si,
>
>                 if (page_nr >= maxpages)
>                         continue;
> -               err = inc_cluster_info_page(si, cluster_info, page_nr);
> +               err = swap_cluster_setup_bad_slot(cluster_info, page_nr);
>                 if (err)
>                         goto err;
>         }
>         for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) {
> -               err = inc_cluster_info_page(si, cluster_info, i);
> +               err = swap_cluster_setup_bad_slot(cluster_info, i);
>                 if (err)
>                         goto err;
>         }
>
> --
> 2.51.0
>