From: Huang Ying <ying.huang@xxxxxxxxx> Subject: mm/swapfile.c: clear si->swap_map[] in swap_free_cluster() si->swap_map[] of the swap entries in cluster needs to be cleared during freeing. Previously, this is done in the caller of swap_free_cluster(). This may cause code duplication (one user now, will add more users later) and lock/unlock cluster unnecessarily. In this patch, the clearing code is moved to swap_free_cluster() to avoid the downside. Link: http://lkml.kernel.org/r/20180827075535.17406-4-ying.huang@xxxxxxxxx Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swapfile.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/mm/swapfile.c~swap-clear-si-swap_map-in-swap_free_cluster +++ a/mm/swapfile.c @@ -932,6 +932,7 @@ static void swap_free_cluster(struct swa struct swap_cluster_info *ci; ci = lock_cluster(si, offset); + memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); cluster_set_count_flag(ci, 0, 0); free_cluster(si, idx); unlock_cluster(ci); @@ -1250,9 +1251,6 @@ void put_swap_page(struct page *page, sw if (free_entries == SWAPFILE_CLUSTER) { unlock_cluster_or_swap_info(si, ci); spin_lock(&si->lock); - ci = lock_cluster(si, offset); - memset(map, 0, SWAPFILE_CLUSTER); - unlock_cluster(ci); mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); swap_free_cluster(si, idx); spin_unlock(&si->lock); _
