I have been able to reproduce this bug, by doing a block-commit on the active layer (as written up in the description). This also does not occur upstream.
Looking in GDB, we are in aio_poll & bdrv_drain_all, but I have not pinpointed a particular patch as a fix.
This should not result in any data loss, as the job should run to completion, and even if stopped early the chain should still be intact. However, it is a bad user experience, as it is not known how long it will be until QEMU is responsive again (and it could potentially be a long time, if there is a lot of data to commit).
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see firstname.lastname@example.org with any questions
according to comment0.
verified this bug with qemu-kvm-rhev-2.6.0-24.
qemu-kvm active during block-mirror.
so, This bug is fixed.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.