diff --git a/fs/namespace.c b/fs/namespace.c
index 9e13ea1e712a..505551013b45 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -6067,7 +6067,8 @@ static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq,
 	ks->bufsize = bufsize;
 
 	if (ks->mask & STATMOUNT_STRING_REQ) {
-		if (bufsize == sizeof(ks->sm))
+		/* Even the reserved empty string needs room past the fixed part. */
+		if (bufsize <= sizeof(ks->sm))
 			return -EOVERFLOW;
 
 		ks->seq.buf = kvmalloc(seq_size, GFP_KERNEL_ACCOUNT);