On Fri, 2025-03-14 at 05:05 +0800, Kemeng Shi wrote:
> The SWAP_MAP_SHMEM indicates last map from shmem. Therefore we can drop
> SWAP_MAP_SHMEM in batch in similar way to drop last 1 flag in batch.
>
> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---
> mm/swapfile.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 0ce0ca08594e..2d0f5d630211 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -192,7 +192,7 @@ static bool swap_is_last_map(struct swap_info_struct *si,
> unsigned char *map_end = map + nr_pages;
> unsigned char count = *map;
>
> - if (swap_count(count) != 1)
> + if (swap_count(count) != 1 && swap_count(count) != SWAP_MAP_SHMEM)
> return false;
>
> while (++map < map_end) {
> @@ -1497,7 +1497,10 @@ static bool swap_entries_put_nr(struct swap_info_struct *si,
> unsigned char count;
> int i;
>
> - if (nr <= 1 || swap_count(data_race(si->swap_map[offset])) != 1)
> + if (nr <= 1)
> + goto fallback;
> + count = swap_count(data_race(si->swap_map[offset]));
> + if (count != 1 && count != SWAP_MAP_SHMEM)
> goto fallback;
> /* cross into another cluster */
> if (nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER)
