On Thu, Apr 27, 2023 at 10:20:28AM +0800, Ming Lei wrote: > Hello Guys, > > I got one report in which buffered write IO hangs in balance_dirty_pages, > after one nvme block device is unplugged physically, then umount can't > succeed. That's a feature, not a bug ... the dd should continue indefinitely? balance_dirty_pages() is sleeping in KILLABLE state, so kill -9 of the dd process should succeed.