On architectures where !SWAP_TABLE_HAS_ZEROFLAG is true, the swap layer
allocates a separate bitmap to track zero-filled pages within a swap cluster.

If a swap device is activated with the SWAP_FLAG_SKIP_ZERO_CHECK flag,
the swap layer no longer checks or tracks zero-filled pages for that
specific device. Therefore, allocating the zero_bitmap is unnecessary.

Signed-off-by: Youngjun Park <youngjun.park@lge.com>
---
 mm/swapfile.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 35cc33698b78..232cc5f9e06e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -446,7 +446,8 @@ static void swap_cluster_free_table(struct swap_cluster_info *ci)
 		 swap_cluster_free_table_folio_rcu_cb);
 }
 
-static int swap_cluster_alloc_table(struct swap_cluster_info *ci, gfp_t gfp)
+static int swap_cluster_alloc_table(struct swap_info_struct *si,
+	struct swap_cluster_info *ci, gfp_t gfp)
 {
 	struct swap_table *table = NULL;
 	struct folio *folio;
@@ -479,6 +480,8 @@ static int swap_cluster_alloc_table(struct swap_cluster_info *ci, gfp_t gfp)
 #endif
 
 #if !SWAP_TABLE_HAS_ZEROFLAG
+	if (si->flags & SWP_SKIP_ZERO_CHECK)
+		return 0;
 	VM_WARN_ON_ONCE(ci->zero_bitmap);
 	ci->zero_bitmap = bitmap_zalloc(SWAPFILE_CLUSTER, gfp);
 	if (!ci->zero_bitmap)
@@ -539,7 +542,7 @@ swap_cluster_populate(struct swap_info_struct *si,
 		lockdep_assert_held(&si->global_cluster_lock);
 	lockdep_assert_held(&ci->lock);
 
-	if (!swap_cluster_alloc_table(ci, __GFP_HIGH | __GFP_NOMEMALLOC |
+	if (!swap_cluster_alloc_table(si, ci, __GFP_HIGH | __GFP_NOMEMALLOC |
 					  __GFP_NOWARN))
 		return ci;
 
@@ -553,7 +556,7 @@ swap_cluster_populate(struct swap_info_struct *si,
 		spin_unlock(&si->global_cluster_lock);
 	local_unlock(&percpu_swap_cluster.lock);
 
-	ret = swap_cluster_alloc_table(ci, __GFP_HIGH | __GFP_NOMEMALLOC |
+	ret = swap_cluster_alloc_table(si, ci, __GFP_HIGH | __GFP_NOMEMALLOC |
 					   GFP_KERNEL);
 
 	/*
@@ -813,7 +816,7 @@ static int swap_cluster_setup_bad_slot(struct swap_info_struct *si,
 
 	ci = cluster_info + idx;
 	/* Need to allocate swap table first for initial bad slot marking. */
-	if (!ci->count && swap_cluster_alloc_table(ci, GFP_KERNEL))
+	if (!ci->count && swap_cluster_alloc_table(si, ci, GFP_KERNEL))
 		return -ENOMEM;
 	spin_lock(&ci->lock);
 	/* Check for duplicated bad swap slots. */
-- 
2.34.1