BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=-20 stuck for 52s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
  pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
    pending: vmstat_shepherd, cache_reap
workqueue events_long: flags=0x0
  pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
    pending: gc_worker
workqueue mm_percpu_wq: flags=0x8
  pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
    pending: vmstat_update
workqueue writeback: flags=0x4e
  pwq 4: cpus=0-1 flags=0x4 nice=0 active=1/256
    in-flight: 5:wb_workfn
workqueue kblockd: flags=0x18
  pwq 1: cpus=0 node=0 flags=0x0 nice=-20 active=1/256
    pending: cfq_kick_queue
workqueue ipv6_addrconf: flags=0x40008
  pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
    pending: addrconf_dad_work
pool 4: cpus=0-1 flags=0x4 nice=0 hung=28s workers=4 idle: 27 90 21