on 3/19/2025 2:08 AM, Kairui Song wrote:
> 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:
Thanks for review. Both ways are acceptable to me. I will keep the
bracket in next version.
Thanks,
Kemeng
>
> Reviewed-by: Kairui Song <kasong@xxxxxxxxxxx>
>
>> unlock_cluster(ci);
>> }
>
>>
>> --
>> 2.30.0
>>
>
