On Fri, 2025-03-14 at 05:05 +0800, Kemeng Shi wrote: > As all callers of swap_entry_range_free() have already ensured slots to > be freed are marked as SWAP_HAS_CACHE while holding the cluster lock, > the BUG_ON check can be safely removed. After this, the function > swap_entry_range_free() could drop any kind of last flag, rename it to > swap_entries_free() and update it's comment accordingly. > > This is a preparation to use swap_entries_free() to drop last 1 and Probably clearer to say drop last ref count instead or drop last 1 > SWAP_MAP_SHMEM flag. > > Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> > --- > mm/swapfile.c | 21 ++++++++++----------- > 1 file changed, 10 insertions(+), 11 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index ba37b9bff586..14b7b37996ff 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -52,9 +52,9 @@ > static bool swap_count_continued(struct swap_info_struct *, pgoff_t, > unsigned char); > static void free_swap_count_continuations(struct swap_info_struct *); > -static void swap_entry_range_free(struct swap_info_struct *si, > - struct swap_cluster_info *ci, > - swp_entry_t entry, unsigned int nr_pages); > +static void swap_entries_free(struct swap_info_struct *si, > + struct swap_cluster_info *ci, > + swp_entry_t entry, unsigned int nr_pages); > static void swap_range_alloc(struct swap_info_struct *si, > unsigned int nr_entries); > static bool folio_swapcache_freeable(struct folio *folio); > @@ -1511,7 +1511,7 @@ static bool swap_entries_put_nr(struct swap_info_struct *si, > for (i = 0; i < nr; i++) > WRITE_ONCE(si->swap_map[offset + i], SWAP_HAS_CACHE); > if (!has_cache) > - swap_entry_range_free(si, ci, entry, nr); > + swap_entries_free(si, ci, entry, nr); > unlock_cluster(ci); > > return has_cache; > @@ -1530,12 +1530,12 @@ static bool swap_entries_put_nr(struct swap_info_struct *si, > } > > /* > - * Drop the last HAS_CACHE flag of swap entries, caller have to > - * ensure all entries belong to the same cgroup. > + * Drop the last flag(1, SWAP_HAS_CACHE or SWAP_MAP_SHMEM) of swap entries, > + * caller have to ensure all entries belong to the same cgroup. Will be nice to modify the above comment: all entries belong to the same cgroup and cluster. Otherwise Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> > > -static void swap_entry_range_free(struct swap_info_struct *si, > - struct swap_cluster_info *ci, > - swp_entry_t entry, unsigned int nr_pages) > +static void swap_entries_free(struct swap_info_struct *si, > + struct swap_cluster_info *ci, > + swp_entry_t entry, unsigned int nr_pages) > { > unsigned long offset = swp_offset(entry); > unsigned char *map = si->swap_map + offset; > @@ -1545,7 +1545,6 @@ static void swap_entry_range_free(struct swap_info_struct *si, > VM_BUG_ON(ci != offset_to_cluster(si, offset + nr_pages - 1)); > > do { > - VM_BUG_ON(*map != SWAP_HAS_CACHE); > *map = 0; > } while (++map < map_end); > > @@ -1605,7 +1604,7 @@ 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_entry_range_free(si, ci, entry, size); > + swap_entries_free(si, ci, entry, size); > else > for (int i = 0; i < size; i++, entry.val++) > swap_entry_put_locked(si, ci, entry, SWAP_HAS_CACHE);