diff --git a/arch/Kconfig b/arch/Kconfig
index 59dee290d94b..9f066785bb71 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -799,7 +799,7 @@ config CFI_CLANG
 	depends on ARCH_SUPPORTS_CFI_CLANG
 	depends on $(cc-option,-fsanitize=kcfi)
 	help
-	  This option enables Clang’s forward-edge Control Flow Integrity
+	  This option enables Clang's forward-edge Control Flow Integrity
 	  (CFI) checking, where the compiler injects a runtime check to each
 	  indirect function call to ensure the target is a valid function with
 	  the correct static type. This restricts possible call targets and
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index b92767d6bdd2..5178c02b21eb 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -417,7 +417,7 @@ static void lkdtm_FAM_BOUNDS(void)
 	pr_err("FAIL: survived access of invalid flexible array member index!\n");
 
 	if (!__has_attribute(__counted_by__))
-		pr_warn("This is expected since this %s was built a compiler supporting __counted_by\n",
+		pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
 			lkdtm_kernel_info);
 	else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
 		pr_expected_config(CONFIG_UBSAN_TRAP);
diff --git a/drivers/net/ethernet/intel/ice/ice_base.c b/drivers/net/ethernet/intel/ice/ice_base.c
index d2fd315556a3..a545a7917e4f 100644
--- a/drivers/net/ethernet/intel/ice/ice_base.c
+++ b/drivers/net/ethernet/intel/ice/ice_base.c
@@ -956,7 +956,7 @@ ice_vsi_cfg_txq(struct ice_vsi *vsi, struct ice_tx_ring *ring,
 int ice_vsi_cfg_single_txq(struct ice_vsi *vsi, struct ice_tx_ring **tx_rings,
 			   u16 q_idx)
 {
-	DEFINE_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
 
 	if (q_idx >= vsi->alloc_txq || !tx_rings || !tx_rings[q_idx])
 		return -EINVAL;
@@ -978,7 +978,7 @@ int ice_vsi_cfg_single_txq(struct ice_vsi *vsi, struct ice_tx_ring **tx_rings,
 static int
 ice_vsi_cfg_txqs(struct ice_vsi *vsi, struct ice_tx_ring **rings, u16 count)
 {
-	DEFINE_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
 	int err = 0;
 	u16 q_idx;
 
diff --git a/drivers/net/ethernet/intel/ice/ice_common.c b/drivers/net/ethernet/intel/ice/ice_common.c
index 4d8111aeb0ff..db4b2844e1f7 100644
--- a/drivers/net/ethernet/intel/ice/ice_common.c
+++ b/drivers/net/ethernet/intel/ice/ice_common.c
@@ -4695,7 +4695,7 @@ ice_dis_vsi_txq(struct ice_port_info *pi, u16 vsi_handle, u8 tc, u8 num_queues,
 		enum ice_disq_rst_src rst_src, u16 vmvf_num,
 		struct ice_sq_cd *cd)
 {
-	DEFINE_FLEX(struct ice_aqc_dis_txq_item, qg_list, q_id, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_dis_txq_item, qg_list, q_id, 1);
 	u16 i, buf_size = __struct_size(qg_list);
 	struct ice_q_ctx *q_ctx;
 	int status = -ENOENT;
@@ -4917,7 +4917,7 @@ int
 ice_dis_vsi_rdma_qset(struct ice_port_info *pi, u16 count, u32 *qset_teid,
 		      u16 *q_id)
 {
-	DEFINE_FLEX(struct ice_aqc_dis_txq_item, qg_list, q_id, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_dis_txq_item, qg_list, q_id, 1);
 	u16 qg_size = __struct_size(qg_list);
 	struct ice_hw *hw;
 	int status = 0;
diff --git a/drivers/net/ethernet/intel/ice/ice_ddp.c b/drivers/net/ethernet/intel/ice/ice_ddp.c
index 7532d11ad7f3..fc91c4d41186 100644
--- a/drivers/net/ethernet/intel/ice/ice_ddp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ddp.c
@@ -1938,8 +1938,8 @@ static enum ice_ddp_state ice_init_pkg_info(struct ice_hw *hw,
  */
 static enum ice_ddp_state ice_get_pkg_info(struct ice_hw *hw)
 {
-	DEFINE_FLEX(struct ice_aqc_get_pkg_info_resp, pkg_info, pkg_info,
-		    ICE_PKG_CNT);
+	DEFINE_RAW_FLEX(struct ice_aqc_get_pkg_info_resp, pkg_info, pkg_info,
+			ICE_PKG_CNT);
 	u16 size = __struct_size(pkg_info);
 	u32 i;
 
@@ -1990,8 +1990,8 @@ static enum ice_ddp_state ice_chk_pkg_compat(struct ice_hw *hw,
 					     struct ice_pkg_hdr *ospkg,
 					     struct ice_seg **seg)
 {
-	DEFINE_FLEX(struct ice_aqc_get_pkg_info_resp, pkg, pkg_info,
-		    ICE_PKG_CNT);
+	DEFINE_RAW_FLEX(struct ice_aqc_get_pkg_info_resp, pkg, pkg_info,
+			ICE_PKG_CNT);
 	u16 size = __struct_size(pkg);
 	enum ice_ddp_state state;
 	u32 i;
diff --git a/drivers/net/ethernet/intel/ice/ice_lag.c b/drivers/net/ethernet/intel/ice/ice_lag.c
index 467372d541d2..f97128b69f87 100644
--- a/drivers/net/ethernet/intel/ice/ice_lag.c
+++ b/drivers/net/ethernet/intel/ice/ice_lag.c
@@ -491,7 +491,7 @@ static void
 ice_lag_move_vf_node_tc(struct ice_lag *lag, u8 oldport, u8 newport,
 			u16 vsi_num, u8 tc)
 {
-	DEFINE_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
 	struct device *dev = ice_pf_to_dev(lag->pf);
 	u16 numq, valq, num_moved, qbuf_size;
 	u16 buf_size = __struct_size(buf);
@@ -849,7 +849,7 @@ static void
 ice_lag_reclaim_vf_tc(struct ice_lag *lag, struct ice_hw *src_hw, u16 vsi_num,
 		      u8 tc)
 {
-	DEFINE_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
 	struct device *dev = ice_pf_to_dev(lag->pf);
 	u16 numq, valq, num_moved, qbuf_size;
 	u16 buf_size = __struct_size(buf);
@@ -1873,7 +1873,7 @@ static void
 ice_lag_move_vf_nodes_tc_sync(struct ice_lag *lag, struct ice_hw *dest_hw,
 			      u16 vsi_num, u8 tc)
 {
-	DEFINE_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
 	struct device *dev = ice_pf_to_dev(lag->pf);
 	u16 numq, valq, num_moved, qbuf_size;
 	u16 buf_size = __struct_size(buf);
diff --git a/drivers/net/ethernet/intel/ice/ice_sched.c b/drivers/net/ethernet/intel/ice/ice_sched.c
index d174a4eeb899..a1525992d14b 100644
--- a/drivers/net/ethernet/intel/ice/ice_sched.c
+++ b/drivers/net/ethernet/intel/ice/ice_sched.c
@@ -237,7 +237,7 @@ static int
 ice_sched_remove_elems(struct ice_hw *hw, struct ice_sched_node *parent,
 		       u32 node_teid)
 {
-	DEFINE_FLEX(struct ice_aqc_delete_elem, buf, teid, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_delete_elem, buf, teid, 1);
 	u16 buf_size = __struct_size(buf);
 	u16 num_groups_removed = 0;
 	int status;
@@ -2219,7 +2219,7 @@ int
 ice_sched_move_nodes(struct ice_port_info *pi, struct ice_sched_node *parent,
 		     u16 num_items, u32 *list)
 {
-	DEFINE_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_move_elem, buf, teid, 1);
 	u16 buf_len = __struct_size(buf);
 	struct ice_sched_node *node;
 	u16 i, grps_movd = 0;
diff --git a/drivers/net/ethernet/intel/ice/ice_switch.c b/drivers/net/ethernet/intel/ice/ice_switch.c
index f84bab80ca42..d4baae8c3b72 100644
--- a/drivers/net/ethernet/intel/ice/ice_switch.c
+++ b/drivers/net/ethernet/intel/ice/ice_switch.c
@@ -1812,7 +1812,7 @@ ice_aq_alloc_free_vsi_list(struct ice_hw *hw, u16 *vsi_list_id,
 			   enum ice_sw_lkup_type lkup_type,
 			   enum ice_adminq_opc opc)
 {
-	DEFINE_FLEX(struct ice_aqc_alloc_free_res_elem, sw_buf, elem, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_alloc_free_res_elem, sw_buf, elem, 1);
 	u16 buf_len = __struct_size(sw_buf);
 	struct ice_aqc_res_elem *vsi_ele;
 	int status;
@@ -2081,7 +2081,7 @@ ice_aq_get_recipe_to_profile(struct ice_hw *hw, u32 profile_id, u8 *r_bitmap,
  */
 int ice_alloc_recipe(struct ice_hw *hw, u16 *rid)
 {
-	DEFINE_FLEX(struct ice_aqc_alloc_free_res_elem, sw_buf, elem, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_alloc_free_res_elem, sw_buf, elem, 1);
 	u16 buf_len = __struct_size(sw_buf);
 	int status;
 
@@ -4418,7 +4418,7 @@ int
 ice_alloc_res_cntr(struct ice_hw *hw, u8 type, u8 alloc_shared, u16 num_items,
 		   u16 *counter_id)
 {
-	DEFINE_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
 	u16 buf_len = __struct_size(buf);
 	int status;
 
@@ -4446,7 +4446,7 @@ int
 ice_free_res_cntr(struct ice_hw *hw, u8 type, u8 alloc_shared, u16 num_items,
 		  u16 counter_id)
 {
-	DEFINE_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
 	u16 buf_len = __struct_size(buf);
 	int status;
 
@@ -4476,7 +4476,7 @@ ice_free_res_cntr(struct ice_hw *hw, u8 type, u8 alloc_shared, u16 num_items,
  */
 int ice_share_res(struct ice_hw *hw, u16 type, u8 shared, u16 res_id)
 {
-	DEFINE_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
+	DEFINE_RAW_FLEX(struct ice_aqc_alloc_free_res_elem, buf, elem, 1);
 	u16 buf_len = __struct_size(buf);
 	u16 res_type;
 	int status;
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index aa691f2119b0..0c7e3dcfe867 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -398,7 +398,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
  * @count: Number of elements in the array; must be compile-time const.
  * @initializer: initializer expression (could be empty for no init).
  */
-#define _DEFINE_FLEX(type, name, member, count, initializer)			\
+#define _DEFINE_FLEX(type, name, member, count, initializer...)			\
 	_Static_assert(__builtin_constant_p(count),				\
 		       "onstack flex array members require compile-time const count"); \
 	union {									\
@@ -408,8 +408,8 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
 	type *name = (type *)&name##_u
 
 /**
- * DEFINE_FLEX() - Define an on-stack instance of structure with a trailing
- * flexible array member.
+ * DEFINE_RAW_FLEX() - Define an on-stack instance of structure with a trailing
+ * flexible array member, when it does not have a __counted_by annotation.
  *
  * @type: structure type name, including "struct" keyword.
  * @name: Name for a variable to define.
@@ -420,7 +420,24 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
  * flexible array member.
  * Use __struct_size(@name) to get compile-time size of it afterwards.
  */
-#define DEFINE_FLEX(type, name, member, count)			\
+#define DEFINE_RAW_FLEX(type, name, member, count)	\
 	_DEFINE_FLEX(type, name, member, count, = {})
 
+/**
+ * DEFINE_FLEX() - Define an on-stack instance of structure with a trailing
+ * flexible array member.
+ *
+ * @TYPE: structure type name, including "struct" keyword.
+ * @NAME: Name for a variable to define.
+ * @MEMBER: Name of the array member.
+ * @COUNTER: Name of the __counted_by member.
+ * @COUNT: Number of elements in the array; must be compile-time const.
+ *
+ * Define a zeroed, on-stack, instance of @TYPE structure with a trailing
+ * flexible array member.
+ * Use __struct_size(@NAME) to get compile-time size of it afterwards.
+ */
+#define DEFINE_FLEX(TYPE, NAME, MEMBER, COUNTER, COUNT)	\
+	_DEFINE_FLEX(TYPE, NAME, MEMBER, COUNT, = { .obj.COUNTER = COUNT, })
+
 #endif /* __LINUX_OVERFLOW_H */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f4a12980a8da..c63a5fbf1f1c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2703,18 +2703,6 @@ config MEMCPY_KUNIT_TEST
 
 	  If unsure, say N.
 
-config MEMCPY_SLOW_KUNIT_TEST
-	bool "Include exhaustive memcpy tests"
-	depends on MEMCPY_KUNIT_TEST
-	default y
-	help
-	  Some memcpy tests are quite exhaustive in checking for overlaps
-	  and bit ranges. These can be very slow, so they are split out
-	  as a separate config, in case they need to be disabled.
-
-	  Note this config option will be replaced by the use of KUnit test
-	  attributes.
-
 config IS_SIGNED_TYPE_KUNIT_TEST
 	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 48a67058f84e..e81e1ac4a919 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -119,6 +119,8 @@ config UBSAN_SIGNED_WRAP
 	bool "Perform checking for signed arithmetic wrap-around"
 	default UBSAN
 	depends on !COMPILE_TEST
+	# The no_sanitize attribute was introduced in GCC with version 8.
+	depends on !CC_IS_GCC || GCC_VERSION >= 80000
 	depends on $(cc-option,-fsanitize=signed-integer-overflow)
 	help
 	  This option enables -fsanitize=signed-integer-overflow which checks
diff --git a/lib/memcpy_kunit.c b/lib/memcpy_kunit.c
index 30e00ef0bf2e..fd16e6ce53d1 100644
--- a/lib/memcpy_kunit.c
+++ b/lib/memcpy_kunit.c
@@ -309,9 +309,6 @@ static void set_random_nonzero(struct kunit *test, u8 *byte)
 
 static void init_large(struct kunit *test)
 {
-	if (!IS_ENABLED(CONFIG_MEMCPY_SLOW_KUNIT_TEST))
-		kunit_skip(test, "Slow test skipped. Enable with CONFIG_MEMCPY_SLOW_KUNIT_TEST=y");
-
 	/* Get many bit patterns. */
 	get_random_bytes(large_src, ARRAY_SIZE(large_src));
 
diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c
index 65e8a72a83bf..4ef31b0bb74d 100644
--- a/lib/overflow_kunit.c
+++ b/lib/overflow_kunit.c
@@ -1172,6 +1172,24 @@ static void castable_to_type_test(struct kunit *test)
 #undef TEST_CASTABLE_TO_TYPE
 }
 
+struct foo {
+	int a;
+	u32 counter;
+	s16 array[] __counted_by(counter);
+};
+
+static void DEFINE_FLEX_test(struct kunit *test)
+{
+	DEFINE_RAW_FLEX(struct foo, two, array, 2);
+	DEFINE_FLEX(struct foo, eight, array, counter, 8);
+	DEFINE_FLEX(struct foo, empty, array, counter, 0);
+
+	KUNIT_EXPECT_EQ(test, __struct_size(two),
+			sizeof(struct foo) + sizeof(s16) + sizeof(s16));
+	KUNIT_EXPECT_EQ(test, __struct_size(eight), 24);
+	KUNIT_EXPECT_EQ(test, __struct_size(empty), sizeof(struct foo));
+}
+
 static struct kunit_case overflow_test_cases[] = {
 	KUNIT_CASE(u8_u8__u8_overflow_test),
 	KUNIT_CASE(s8_s8__s8_overflow_test),
@@ -1194,6 +1212,7 @@ static struct kunit_case overflow_test_cases[] = {
 	KUNIT_CASE(overflows_type_test),
 	KUNIT_CASE(same_type_test),
 	KUNIT_CASE(castable_to_type_test),
+	KUNIT_CASE(DEFINE_FLEX_test),
 	{}
 };