[ 2039.048119] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2039.048121] sync            D 0000000000000001     0 10454   8201 0x00000000
[ 2039.048124]  ffff8801c0721cb8 0000000000000082 0000000000000000 000000000000000e
[ 2039.048127]  ffff8801c0721fd8 ffff8801c0721fd8 ffff8801c0721fd8 0000000000013780
[ 2039.048129]  ffff880211c444d0 ffff8801d1dd96f0 ffff8801c0721ce8 7fffffffffffffff
[ 2039.048132] Call Trace:
[ 2039.048138]  [<ffffffff81657d8f>] schedule+0x3f/0x60
[ 2039.048140]  [<ffffffff816583d5>] schedule_timeout+0x2a5/0x320
[ 2039.048143]  [<ffffffff8101ae69>] ? sched_clock+0x9/0x10
[ 2039.048146]  [<ffffffff81030888>] ? native_smp_send_reschedule+0x48/0x60
[ 2039.048149]  [<ffffffff81052002>] ? ttwu_queue+0x92/0xd0
[ 2039.048151]  [<ffffffff81657bcf>] wait_for_common+0xdf/0x180
[ 2039.048154]  [<ffffffff811a69d0>] ? __sync_filesystem+0x90/0x90
[ 2039.048157]  [<ffffffff8105fae0>] ? try_to_wake_up+0x200/0x200
[ 2039.048159]  [<ffffffff811a69d0>] ? __sync_filesystem+0x90/0x90
[ 2039.048161]  [<ffffffff81657d4d>] wait_for_completion+0x1d/0x20
[ 2039.048163]  [<ffffffff8119f6dd>] writeback_inodes_sb_nr+0x7d/0xa0
[ 2039.048165]  [<ffffffff8119f94e>] writeback_inodes_sb+0x2e/0x40
[ 2039.048167]  [<ffffffff811a698e>] __sync_filesystem+0x4e/0x90
[ 2039.048169]  [<ffffffff811a69ef>] sync_one_sb+0x1f/0x30
[ 2039.048172]  [<ffffffff8117b435>] iterate_supers+0xa5/0x100
[ 2039.048174]  [<ffffffff811a6aa0>] sys_sync+0x30/0x70
[ 2039.048177]  [<ffffffff81662282>] system_call_fastpath+0x16/0x1b