System hang due to I/O stuck in cfq scheduler

Issue

System hung and was forced crashed. Various processes stuck waiting for I/O but no requests inflight to the disks:

crash> dev -d
MAJOR GENDISK            NAME       REQUEST_QUEUE      TOTAL ASYNC  SYNC   DRV
   11 ffff880532a73c00   sr0        ffff880532390e68       0     0     0     0
    8 ffff880532168400   sda        ffff880532390338     166   159     7     0
    8 ffff880532167000   sdb        ffff8805319c8ea8       0     0     0     0
    8 ffff880532167c00   sdc        ffff8805319c8378      17     5    12     0
    8 ffff880532066400   sdd        ffff8805319ccee8       0     0     0     0
    8 ffff880532066c00   sde        ffff8805319cc3b8       0     0     0     0
    8 ffff880532065400   sdf        ffff8805319d0f28       0     0     0     0
    8 ffff880532065c00   sdg        ffff8805319d03f8       0     0     0     0
    8 ffff880532063400   sdh        ffff880531afefa8       0     0     0     0
    8 ffff880532063c00   sdi        ffff880531afe478       0     0     0     0
    8 ffff880532062400   sdj        ffff880531b00fe8       0     0     0     0
  253 ffff880532000000   dm-0       ffff880531497028       0     0     0     0
  253 ffff88053212a400   dm-1       ffff880531b004b8       0     0     0     0