diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6b3e155b70bf..72bc906d8bc7 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -106,6 +106,18 @@
 /* Avoid kmemleak tracing */
 #define SLAB_NOLEAKTRACE	((slab_flags_t __force)0x00800000U)
 
+/*
+ * Prevent merging with compatible kmem caches. This flag should be used
+ * cautiously. Valid use cases:
+ *
+ * - caches created for self-tests (e.g. kunit)
+ * - general caches created and used by a subsystem, only when a
+ *   (subsystem-specific) debug option is enabled
+ * - performance critical caches, should be very rare and consulted with slab
+ *   maintainers, and not used together with CONFIG_SLUB_TINY
+ */
+#define SLAB_NO_MERGE		((slab_flags_t __force)0x01000000U)
+
 /* Fault injection mark */
 #ifdef CONFIG_FAILSLAB
 # define SLAB_FAILSLAB		((slab_flags_t __force)0x02000000U)
diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c
index 6aee19a79236..9e008a336d9f 100644
--- a/mm/kfence/kfence_test.c
+++ b/mm/kfence/kfence_test.c
@@ -191,11 +191,10 @@ static size_t setup_test_cache(struct kunit *test, size_t size, slab_flags_t fla
 	kunit_info(test, "%s: size=%zu, ctor=%ps\n", __func__, size, ctor);
 
 	/*
-	 * Use SLAB_NOLEAKTRACE to prevent merging with existing caches. Any
-	 * other flag in SLAB_NEVER_MERGE also works. Use SLAB_ACCOUNT to
-	 * allocate via memcg, if enabled.
+	 * Use SLAB_NO_MERGE to prevent merging with existing caches.
+	 * Use SLAB_ACCOUNT to allocate via memcg, if enabled.
 	 */
-	flags |= SLAB_NOLEAKTRACE | SLAB_ACCOUNT;
+	flags |= SLAB_NO_MERGE | SLAB_ACCOUNT;
 	test_cache = kmem_cache_create("test", size, 1, flags, ctor);
 	KUNIT_ASSERT_TRUE_MSG(test, test_cache, "could not create cache");
 
diff --git a/mm/slab.h b/mm/slab.h
index f01ac256a8f5..9005ddc51cf8 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -294,11 +294,11 @@ static inline bool is_kmalloc_cache(struct kmem_cache *s)
 #if defined(CONFIG_SLAB)
 #define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
 			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
-			  SLAB_ACCOUNT)
+			  SLAB_ACCOUNT | SLAB_NO_MERGE)
 #elif defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
 			  SLAB_TEMPORARY | SLAB_ACCOUNT | \
-			  SLAB_NO_USER_FLAGS | SLAB_KMALLOC)
+			  SLAB_NO_USER_FLAGS | SLAB_KMALLOC | SLAB_NO_MERGE)
 #else
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
 #endif
@@ -319,6 +319,7 @@ static inline bool is_kmalloc_cache(struct kmem_cache *s)
 			      SLAB_TEMPORARY | \
 			      SLAB_ACCOUNT | \
 			      SLAB_KMALLOC | \
+			      SLAB_NO_MERGE | \
 			      SLAB_NO_USER_FLAGS)
 
 bool __kmem_cache_empty(struct kmem_cache *);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 607249785c07..0e0a617eae7d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -47,7 +47,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
  */
 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
 		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
-		SLAB_FAILSLAB | kasan_never_merge())
+		SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())
 
 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
 			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)