Comment 32 for bug 1852001

The last time I got it to hang long enough to produce a backtrace it showed:

[1560556.660010] INFO: task vgs:3103183 blocked for more than 1105 seconds.
[1560556.660012] Tainted: G U OE 5.4.0-40-lowlatency #44-Ubuntu
[1560556.660013] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[1560556.660014] vgs D 0 3103183 411358 0x80004004
[1560556.660016] Call Trace:
[1560556.660021] __schedule+0x2e5/0x750
[1560556.660023] schedule+0x49/0xd0
[1560556.660024] schedule_timeout+0x21a/0x300
[1560556.660027] ? call_rcu+0x10/0x20
[1560556.660030] ? __percpu_ref_switch_mode+0xec/0x1b0
[1560556.660031] wait_for_completion+0xa3/0x100
[1560556.660033] ? wake_up_q+0x70/0x70
[1560556.660036] exit_aio+0xe7/0xf0
[1560556.660038] mmput+0x22/0x120
[1560556.660039] do_exit+0x2f8/0xae0
[1560556.660041] ? finish_task_switch+0x75/0x250
[1560556.660042] do_group_exit+0x43/0xa0
[1560556.660044] get_signal+0x13e/0x8f0
[1560556.660046] ? hrtimer_cancel+0x15/0x20
[1560556.660047] ? read_events+0x14f/0x160
[1560556.660049] do_signal+0x34/0x6e0
[1560556.660050] ? hrtimer_init_sleeper+0xb0/0xb0
[1560556.660052] ? do_io_getevents+0x7a/0xf0
[1560556.660054] exit_to_usermode_loop+0xbf/0x160
[1560556.660055] do_syscall_64+0x163/0x190
[1560556.660057] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[1560556.660058] RIP: 0033:0x7f3b1269a70d
[1560556.660062] Code: Bad RIP value.
[1560556.660062] RSP: 002b:00007fffd99f2f08 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0
[1560556.660064] RAX: fffffffffffffffc RBX: 00007f3b1228e6c0 RCX: 00007f3b1269a70d
[1560556.660064] RDX: 0000000000000040 RSI: 0000000000000001 RDI: 00007f3b12a7e000
[1560556.660065] RBP: 00007f3b12a7e000 R08: 0000000000000000 R09: 0000000200000016
[1560556.660065] R10: 00007fffd99f2f90 R11: 0000000000000246 R12: 0000000000000001
[1560556.660066] R13: 0000000000000002 R14: 0000000000000040 R15: 00007fffd99f2f90