Comment 4 for bug 1805778

Seems like a process is still running at umount time and a re-mount fails. I think it snowballs after that.

[ 1209.031563] Mount point: /mnt/vfat-test-15951
[ 1209.032392] Started, PID 67047
[ 1224.249103] stress-ng now terminated
[ 1224.249203] Stopped, PID 67047 (after 14 seconds)
[ 1224.249312] umounting vfat
[ 1224.468077] umounting tmpfs
[ 1224.548526] Testing: --verify --times --metrics-brief --syslog --keep-name -t 10s --hdd 2 --hdd-opts sync,wr-rnd,rd-rnd,fadv-willneed,fadv-rnd --lockf 2 --seek 2 --aio 2 --aio-requests 32 --dentry 2 --dir 2 --dentry-order stride --fallocate 2 --fstat 2 --dentries 100 --lease 2 --open 2 --rename 2 --hdd-bytes 4M --fallocate-bytes 4M --chdir 2 --rename 2 --hdd-write-size 512
[ 1225.606221] Created loop image /mnt/vfat-test-15951/vfat-loop-data
[ 1225.684994] ubuntu_vfat_str (15951): drop_caches: 1
[ 1225.692320] ubuntu_vfat_str (15951): drop_caches: 2
[ 1225.695075] ubuntu_vfat_str (15951): drop_caches: 3
[ 1226.046191] VFAT options: fmask=777
[ 1226.046241] Stress test: /home/ubuntu/autotest/client/tmp/ubuntu_vfat_stress/src/stress-ng/stress-ng --verify --times --metrics-brief --syslog --keep-name -t 10s --hdd 2 --hdd-opts sync,wr-rnd,rd-rnd,fadv-willneed,fadv-rnd --lockf 2 --seek 2 --aio 2 --aio-requests 32 --dentry 2 --dir 2 --dentry-order stride --fallocate 2 --fstat 2 --dentries 100 --lease 2 --open 2 --rename 2 --hdd-bytes 4M --fallocate-bytes 4M --chdir 2 --rename 2 --hdd-write-size 512
[ 1226.046261] Mount point: /mnt/vfat-test-15951
[ 1226.046733] Started, PID 107847
[ 1230.696549] stress-ng now terminated
[ 1230.696689] Stopped, PID 107847 (after 4 seconds)
[ 1230.696870] umounting vfat
[ 1230.729214] umount vfat /mnt/vfat-test-15951 failed
[ 1230.729283] umounting tmpfs
[ 1230.730847] umount /mnt/vfat-test-15951 failed
[ 1230.746365] /mnt/vfat-test-15951 is already mounted!