Hi, I am writing to ask why jbd2 might freeze in kjournald2()? I am asking this because since blk-mq commit bc27c01b5c46 (blk-mq: Do not invoke .queue_rq() for a stopped queue), the I/O request will be queued when the queue is stopped, that is, when OS is frozen (e.g., during xen live migration or "echo freeze > /sys/power/state" in kvm guest). I think it should be fine to not freeze jbd2. Why would kjournald2() freeze to avoid submitting I/O? Is it because of what is mentioned in code that "The simpler the better", or there is any other reason? Thank you very much! Dongli Zhang
