On Fri, Nov 20, 2020 at 05:14:28PM -0600, Eric W. Biederman wrote: > > diff --git a/fs/file.c b/fs/file.c > index 5861c4f89419..6448523ca29e 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -865,6 +865,21 @@ struct file *fget_task(struct task_struct *task, unsigned int fd) > return file; > } > > +struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd) > +{ > + /* Must be called with rcu_read_lock held */ Eric, maybe worth to have something like RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious task_lookup_fd_rcu() usage"); here?