Hi, this patch series fixes oops and possible deadlocks as reported by syzbot [1] [2]. The second patch in the series (from Tetsuo) fixes the oops, the remaining patches are cleaning up the locking in the loop driver so that we can in the end reasonably easily switch to rereading partitions without holding mutex protecting the loop device. I have lightly tested the patches by creating, deleting, and modifying loop devices but if there's some more comprehensive loopback device testsuite, I can try running it. Review is welcome! Changes since v1: * Added patch moving fput() calls in loop_change_fd() from under loop_ctl_mutex * Fixed bug in loop_control_ioctl() where it failed to return error properly Honza [1] https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3 [2] https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889
