On Thu, Jul 25, 2019 at 6:26 AM Cyril Hrubis <chru...@suse.cz> wrote: > > This looks like mkfs.vfat got EBUSY after the loop device was > succesfully umounted.
Hmm. Smells like the RCU-delaying got triggered again. We have that "synchronize_rcu_expedited()" in namespace_unlock(), which is so that everything should be done by the time we return to user space. Al, maybe that RCU synchronization should be after the mntput()s? Linus