diff --git a/fs/open.c b/fs/open.c
index 50a46501bcc9..8cdb2b675867 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -993,8 +993,6 @@ static inline int build_open_flags(const struct open_how *how,
 		return -EINVAL;
 	if (how->resolve & ~VALID_RESOLVE_FLAGS)
 		return -EINVAL;
-	if (memchr_inv(how->__padding, 0, sizeof(how->__padding)))
-		return -EINVAL;
 
 	/* Deal with the mode. */
 	if (WILL_CREATE(flags)) {
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index d886bdb585e4..5aaadfd79dd5 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -101,22 +101,21 @@
 #define AT_RECURSIVE		0x8000	/* Apply to the entire subtree */
 
 /*
- * Arguments for how openat2(2) should open the target path. If @resolve is
- * zero, then openat2(2) operates very similarly to openat(2).
+ * Arguments for how openat2(2) should open the target path. If only @flags and
+ * @mode are non-zero, then openat2(2) operates very similarly to openat(2).
  *
- * However, unlike openat(2), unknown bits in @flags result in -EINVAL rather
- * than being silently ignored. @mode must be zero unless one of {O_CREAT,
- * O_TMPFILE} are set.
+ * However, unlike openat(2), unknown or invalid bits in @flags result in
+ * -EINVAL rather than being silently ignored. @mode must be zero unless one of
+ *  {O_CREAT, O_TMPFILE} are set.
  *
  * @flags: O_* flags.
  * @mode: O_CREAT/O_TMPFILE file mode.
  * @resolve: RESOLVE_* flags.
  */
 struct open_how {
-	__aligned_u64 flags;
-	__u16 mode;
-	__u16 __padding[3]; /* must be zeroed */
-	__aligned_u64 resolve;
+	__u64 flags;
+	__u64 mode;
+	__u64 resolve;
 };
 
 #define OPEN_HOW_SIZE_VER0	24 /* sizeof first published struct */
diff --git a/tools/testing/selftests/openat2/helpers.h b/tools/testing/selftests/openat2/helpers.h
index 43ca5ceab6e3..a6ea27344db2 100644
--- a/tools/testing/selftests/openat2/helpers.h
+++ b/tools/testing/selftests/openat2/helpers.h
@@ -36,10 +36,9 @@
  * @resolve: RESOLVE_* flags.
  */
 struct open_how {
-	__aligned_u64 flags;
-	__u16 mode;
-	__u16 __padding[3]; /* must be zeroed */
-	__aligned_u64 resolve;
+	__u64 flags;
+	__u64 mode;
+	__u64 resolve;
 };
 
 #define OPEN_HOW_SIZE_VER0	24 /* sizeof first published struct */
diff --git a/tools/testing/selftests/openat2/openat2_test.c b/tools/testing/selftests/openat2/openat2_test.c
index 0b64fedc008b..b386367c606b 100644
--- a/tools/testing/selftests/openat2/openat2_test.c
+++ b/tools/testing/selftests/openat2/openat2_test.c
@@ -40,7 +40,7 @@ struct struct_test {
 	int err;
 };
 
-#define NUM_OPENAT2_STRUCT_TESTS 10
+#define NUM_OPENAT2_STRUCT_TESTS 7
 #define NUM_OPENAT2_STRUCT_VARIATIONS 13
 
 void test_openat2_struct(void)
@@ -57,20 +57,6 @@ void test_openat2_struct(void)
 		  .arg.inner.flags = O_RDONLY,
 		  .size = sizeof(struct open_how_ext) },
 
-		/* Normal struct with broken padding. */
-		{ .name = "normal struct (non-zero padding[0])",
-		  .arg.inner.flags = O_RDONLY,
-		  .arg.inner.__padding = {0xa0, 0x00, 0x00},
-		  .size = sizeof(struct open_how_ext), .err = -EINVAL },
-		{ .name = "normal struct (non-zero padding[1])",
-		  .arg.inner.flags = O_RDONLY,
-		  .arg.inner.__padding = {0x00, 0x1a, 0x00},
-		  .size = sizeof(struct open_how_ext), .err = -EINVAL },
-		{ .name = "normal struct (non-zero padding[2])",
-		  .arg.inner.flags = O_RDONLY,
-		  .arg.inner.__padding = {0x00, 0x00, 0xef},
-		  .size = sizeof(struct open_how_ext), .err = -EINVAL },
-
 		/* TODO: Once expanded, check zero-padding. */
 
 		/* Smaller than version-0 struct. */
@@ -169,7 +155,7 @@ struct flag_test {
 	int err;
 };
 
-#define NUM_OPENAT2_FLAG_TESTS 21
+#define NUM_OPENAT2_FLAG_TESTS 23
 
 void test_openat2_flags(void)
 {
@@ -214,9 +200,15 @@ void test_openat2_flags(void)
 		{ .name = "invalid how.mode and O_CREAT",
 		  .how.flags = O_CREAT,
 		  .how.mode = 0xFFFF, .err = -EINVAL },
+		{ .name = "invalid (very large) how.mode and O_CREAT",
+		  .how.flags = O_CREAT,
+		  .how.mode = 0xC000000000000000ULL, .err = -EINVAL },
 		{ .name = "invalid how.mode and O_TMPFILE",
 		  .how.flags = O_TMPFILE | O_RDWR,
 		  .how.mode = 0x1337, .err = -EINVAL },
+		{ .name = "invalid (very large) how.mode and O_TMPFILE",
+		  .how.flags = O_TMPFILE | O_RDWR,
+		  .how.mode = 0x0000A00000000000ULL, .err = -EINVAL },
 
 		/* ->resolve must only contain RESOLVE_* flags. */
 		{ .name = "invalid how.resolve and O_RDONLY",
