On 08/05/2024 23:40, Barry Song wrote:
> From: Barry Song <v-songbaohua@xxxxxxxx>
>
> To streamline maintenance efforts, we propose removing the implementation
> of swap_free(). Instead, we can simply invoke swap_free_nr() with nr
> set to 1. swap_free_nr() is designed with a bitmap consisting of only
> one long, resulting in overhead that can be ignored for cases where nr
> equals 1.
>
> A prime candidate for leveraging swap_free_nr() lies within
> kernel/power/swap.c. Implementing this change facilitates the adoption
> of batch processing for hibernation.
>
> Suggested-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Acked-by: Chris Li <chrisl@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx>
> ---
> include/linux/swap.h | 10 +++++-----
> kernel/power/swap.c | 5 ++---
> mm/swapfile.c | 17 ++++-------------
> 3 files changed, 11 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index d1d35e92d7e9..48131b869a4d 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -482,7 +482,6 @@ extern int add_swap_count_continuation(swp_entry_t, gfp_t);
> extern void swap_shmem_alloc(swp_entry_t);
> extern int swap_duplicate(swp_entry_t);
> extern int swapcache_prepare(swp_entry_t);
> -extern void swap_free(swp_entry_t);
> extern void swap_free_nr(swp_entry_t entry, int nr_pages);
> extern void swapcache_free_entries(swp_entry_t *entries, int n);
> extern void free_swap_and_cache_nr(swp_entry_t entry, int nr);
> @@ -561,10 +560,6 @@ static inline int swapcache_prepare(swp_entry_t swp)
> return 0;
> }
>
> -static inline void swap_free(swp_entry_t swp)
> -{
> -}
> -
> static inline void swap_free_nr(swp_entry_t entry, int nr_pages)
> {
> }
> @@ -613,6 +608,11 @@ static inline void free_swap_and_cache(swp_entry_t entry)
> free_swap_and_cache_nr(entry, 1);
> }
>
> +static inline void swap_free(swp_entry_t entry)
> +{
> + swap_free_nr(entry, 1);
> +}
> +
> #ifdef CONFIG_MEMCG
> static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
> {
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 5bc04bfe2db1..75bc9e3f9d59 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -200,12 +200,11 @@ void free_all_swap_pages(int swap)
>
> while ((node = swsusp_extents.rb_node)) {
> struct swsusp_extent *ext;
> - unsigned long offset;
>
> ext = rb_entry(node, struct swsusp_extent, node);
> rb_erase(node, &swsusp_extents);
> - for (offset = ext->start; offset <= ext->end; offset++)
> - swap_free(swp_entry(swap, offset));
> + swap_free_nr(swp_entry(swap, ext->start),
> + ext->end - ext->start + 1);
>
> kfree(ext);
> }
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index ec12f2b9d229..99e701620562 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1343,19 +1343,6 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
> swap_range_free(p, offset, 1);
> }
>
> -/*
> - * Caller has made sure that the swap device corresponding to entry
> - * is still around or has not been recycled.
> - */
> -void swap_free(swp_entry_t entry)
> -{
> - struct swap_info_struct *p;
> -
> - p = _swap_info_get(entry);
> - if (p)
> - __swap_entry_free(p, entry);
> -}
> -
> static void cluster_swap_free_nr(struct swap_info_struct *sis,
> unsigned long offset, int nr_pages)
> {
> @@ -1385,6 +1372,10 @@ static void cluster_swap_free_nr(struct swap_info_struct *sis,
> unlock_cluster_or_swap_info(sis, ci);
> }
>
> +/*
> + * Caller has made sure that the swap device corresponding to entry
> + * is still around or has not been recycled.
> + */
> void swap_free_nr(swp_entry_t entry, int nr_pages)
> {
> int nr;
