In swap_range_free(), we update inuse_pages then do some cleanups (arch invalidation, zswap invalidation, swap cache cleanups, etc). During swapoff, try_to_unuse() uses inuse_pages to make sure all swap entries are freed. Make sure we only update inuse_pages after we are done with the cleanups. In practice, this shouldn't matter, because swap_range_free() is called with the swap info lock held, and the swapoff code will spin for that lock after try_to_unuse() anyway. The goal is to make it obvious and more future proof that once try_to_unuse() returns, all cleanups are done. This also facilitates a following zswap cleanup patch which uses this fact to simplify zswap_swapoff(). Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> --- mm/swapfile.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 556ff7347d5f0..2fedb148b9404 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -737,8 +737,6 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset, if (was_full && (si->flags & SWP_WRITEOK)) add_to_avail_list(si); } - atomic_long_add(nr_entries, &nr_swap_pages); - WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); if (si->flags & SWP_BLKDEV) swap_slot_free_notify = si->bdev->bd_disk->fops->swap_slot_free_notify; @@ -752,6 +750,8 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset, offset++; } clear_shadow_from_swap_cache(si->type, begin, end); + atomic_long_add(nr_entries, &nr_swap_pages); + WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); } static void set_cluster_next(struct swap_info_struct *si, unsigned long next) -- 2.43.0.429.g432eaa2c6b-goog
