On Tue, Mar 18, 2025 at 2:10 PM Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> wrote:
>
> In swap_entry_put_locked(), we will set slot to SWAP_HAS_CACHE before
> using swap_entries_free() to do actual swap entry freeing. This
> introduce an unnecessary intermediate state.
> By using swap_entries_free() in swap_entry_put_locked(), we can
> eliminate the need to set slot to SWAP_HAS_CACHE.
> This change would make the behavior of swap_entry_put_locked() more
> consistent with other put() operations which will do actual free work
> after put last reference.
>
> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
> Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---
> mm/swapfile.c | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 0aa7ce82c013..40e41e514813 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1348,9 +1348,11 @@ static struct swap_info_struct *_swap_info_get(swp_entry_t entry)
> }
>
> static unsigned char swap_entry_put_locked(struct swap_info_struct *si,
> - unsigned long offset,
> + struct swap_cluster_info *ci,
> + swp_entry_t entry,
> unsigned char usage)
> {
> + unsigned long offset = swp_offset(entry);
> unsigned char count;
> unsigned char has_cache;
>
> @@ -1382,7 +1384,7 @@ static unsigned char swap_entry_put_locked(struct swap_info_struct *si,
> if (usage)
> WRITE_ONCE(si->swap_map[offset], usage);
> else
> - WRITE_ONCE(si->swap_map[offset], SWAP_HAS_CACHE);
> + swap_entries_free(si, ci, entry, 1);
>
> return usage;
> }
> @@ -1461,9 +1463,7 @@ static unsigned char swap_entry_put(struct swap_info_struct *si,
> unsigned char usage;
>
> ci = lock_cluster(si, offset);
> - usage = swap_entry_put_locked(si, offset, 1);
> - if (!usage)
> - swap_entries_free(si, ci, swp_entry(si->type, offset), 1);
> + usage = swap_entry_put_locked(si, ci, entry, 1);
> unlock_cluster(ci);
>
> return usage;
> @@ -1551,8 +1551,8 @@ static void cluster_swap_free_nr(struct swap_info_struct *si,
>
> ci = lock_cluster(si, offset);
> do {
> - if (!swap_entry_put_locked(si, offset, usage))
> - swap_entries_free(si, ci, swp_entry(si->type, offset), 1);
> + swap_entry_put_locked(si, ci, swp_entry(si->type, offset),
> + usage);
> } while (++offset < end);
> unlock_cluster(ci);
> }
> @@ -1596,12 +1596,9 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry)
> ci = lock_cluster(si, offset);
> if (swap_only_has_cache(si, offset, size))
> swap_entries_free(si, ci, entry, size);
> - else {
> - for (int i = 0; i < size; i++, entry.val++) {
> - if (!swap_entry_put_locked(si, offset + i, SWAP_HAS_CACHE))
> - swap_entries_free(si, ci, entry, 1);
> - }
> - }
> + else
> + for (int i = 0; i < size; i++, entry.val++)
> + swap_entry_put_locked(si, ci, entry, SWAP_HAS_CACHE);
I'd prefer you keep the bracket here for more readability, and maybe
add bracket for the whole if statement, just a tiny nitpick so still:
Reviewed-by: Kairui Song <kasong@xxxxxxxxxxx>
> unlock_cluster(ci);
> }
>
> --
> 2.30.0
>
