Hi Dan, There are two different BUG_ON() incidents get recently reported on Launchpad [1]. The first one is BUG_ON(dev->written) in ops_run_biodrain(). The second one (comment #23) is BUG_ON(!test_bit(R5_UPTODATE, &dev->flags)) in handle_parity_checks5(). I am not familiar with raid 5 so I am not sure these BUG_ON() are expected to be hit. [1] https://bugs.launchpad.net/bugs/1780628 Kai-Heng
