John Wren Kennedy

When a solution is found for this bug, we should be sure not to let the work done in https://github.com/openzfs/zfs/pull/12335 be lost, and include those tests.

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/25076/consoleFull ``` 00:25:07 + umount /var/crash 00:25:07 + zfs umount rpool/ROOT/****.8mx0vz7/root 00:25:07 umount: /mnt/****.8mx0vz7: target is busy. 00:25:07 cannot unmount '/mnt/****.8mx0vz7': umount failed 00:25:07 E: config/hooks/90-raw-disk-image.binary failed (exit non-zero). You...

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/39865/console

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/41427/consoleFull

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/41825/console

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/42017/console ``` 00:25:12 + zfs umount rpool/ROOT/****.9jUaNcs/root 00:25:12 umount: /mnt/****.9jUaNcs: target is busy. 00:25:12 cannot unmount '/mnt/****.9jUaNcs': umount failed 00:25:12 E: config/hooks/90-raw-disk-image.binary failed (exit non-zero). You should check for errors....

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build-stage1/job/post-push/53859/console ``` 23:25:13 Found initrd image: /boot/initrd.img-5.4.0-42-generic 23:25:13 done 23:25:13 + chroot /mnt/****.lUlFaFQ umount /mnt 23:25:13 + for dir in /dev /proc /sys 23:25:13 + umount -R /mnt/****.lUlFaFQ/dev 23:25:13 +...

http://ops.jenkins.delphix.com/job/devops-gate/job/master/job/appliance-build/job/6.0/job/stage/job/nightly/616/

http://ops.jenkins.delphix.com/job/appliance-build-stage1/job/post-push/6636/console ``` 23:25:13 + umount /var/crash 23:25:13 + zfs umount rpool/ROOT/delphix.bvwzhD8/root 23:25:13 umount: /mnt/delphix.bvwzhD8: target is busy. 23:25:13 cannot unmount '/mnt/delphix.bvwzhD8': umount failed 23:25:13 E: config/hooks/90-raw-disk-image.binary failed (exit non-zero). You...

Seen twice in http://ops.jenkins.delphix.com/job/appliance-build/job/6.0/job/stage/job/post-push/322/console and again once each in http://ops.jenkins.delphix.com/job/appliance-build/job/6.0/job/stage/job/post-push/323/ and http://ops.jenkins.delphix.com/job/appliance-build/job/master/job/nightly/85/