diff --git a/io_uring/register.c b/io_uring/register.c
index a59589249fce..b1772a470bf6 100644
--- a/io_uring/register.c
+++ b/io_uring/register.c
@@ -618,6 +618,7 @@ static int io_register_mem_region(struct io_ring_ctx *ctx, void __user *uarg)
 	if (ret)
 		return ret;
 	if (copy_to_user(rd_uptr, &rd, sizeof(rd))) {
+		guard(mutex)(&ctx->mmap_lock);
 		io_free_region(ctx, &ctx->param_region);
 		return -EFAULT;
 	}