Comment 5 for bug 1914221

[ 491.663188] INFO: task stress-ng-dev:3184 blocked for more than 120 seconds.
[ 491.663193] Tainted: G W 4.15.0-135-lowlatency #139-Ubuntu
[ 491.663194] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 491.663196] stress-ng-dev D 0 3184 3164 0x00000004
[ 491.663202] Call Trace:
[ 491.663223] __schedule+0x250/0x8a0
[ 491.663237] ? ioapic_irq_get_chip_state+0x69/0x80
[ 491.664327] schedule+0x33/0x90
[ 491.664335] synchronize_irq+0x74/0xb0
[ 491.664341] ? wait_woken+0x80/0x80
[ 491.664349] uart_port_shutdown+0x4c/0x50
[ 491.664352] uart_tty_port_shutdown+0x47/0xb0
[ 491.664358] tty_port_shutdown+0x80/0x90
[ 491.664362] tty_port_close+0x3d/0x70
[ 491.664365] uart_close+0x33/0xa0
[ 491.664369] tty_release+0x124/0x610
[ 491.664377] __fput+0xe4/0x220
[ 491.664382] ____fput+0xe/0x10
[ 491.664389] task_work_run+0x7f/0xa0
[ 491.664395] exit_to_usermode_loop+0xc0/0xd0
[ 491.664399] do_syscall_64+0x121/0x130
[ 491.664405] entry_SYSCALL_64_after_hwframe+0x41/0xa6
[ 491.664411] RIP: 0033:0x7fc4abd669c7
[ 491.664414] RSP: 002b:00007fc4a7fcdbf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
[ 491.664417] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007fc4abd669c7
[ 491.664419] RDX: 0000000000000000 RSI: 000000000000540d RDI: 0000000000000004
[ 491.664420] RBP: 00007fc4a7fcde90 R08: 0000000000000000 R09: 0000000000000001
[ 491.664422] R10: fffffffffffffea1 R11: 0000000000000293 R12: 000055dfb749b2a8
[ 491.664424] R13: 0000000000000004 R14: 0000000000000004 R15: 00007fff992be370