On Mon, Dec 05, 2022 at 09:51:39AM -0800, Nhat Pham wrote: > + if (!access_ok(cstat, sizeof(struct cachestat))) > + return -EFAULT; What for? You are using copy_to_user() later, right? > + f = fdget(fd); > + if (f.file) { It would be easier to read if you inverted the condition here.