syzbot

INFO: task getty:2167 blocked for more than 140 seconds.
      Not tainted 4.9.169+ #42
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
getty           D28640  2167      1 0x00000000
 ffff8801c9068000 0000000000000000 ffff8801db721000 ffff8801da6b2f80
 ffff8801db721018 ffff8801c9037990 ffffffff8280152e 0000000000000246
 ffff8801c9068000 0000000000000000 ffff8801db7218f0 1ffff10039206f21
Call Trace:
 [<0000000090d20601>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000a5bd9856>] __rt_mutex_slowlock+0x99/0x290 kernel/locking/rtmutex.c:1221
 [<000000002788e57c>] rt_mutex_slowlock+0x199/0x4c0 kernel/locking/rtmutex.c:1293
 [<000000009a3b49db>] rt_mutex_fastlock kernel/locking/rtmutex.c:1439 [inline]
 [<000000009a3b49db>] rt_mutex_lock+0x2d/0x40 kernel/locking/rtmutex.c:1499
 [<00000000a0e4ff6b>] process_notifier drivers/misc/uid_sys_stats.c:636 [inline]
 [<00000000a0e4ff6b>] process_notifier+0x96/0x670 drivers/misc/uid_sys_stats.c:625
 [<00000000bc854e50>] notifier_call_chain+0xb4/0x1d0 kernel/notifier.c:93
 [<00000000836265f9>] __blocking_notifier_call_chain kernel/notifier.c:317 [inline]
 [<00000000836265f9>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 [<00000000836265f9>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 [<00000000836265f9>] blocking_notifier_call_chain+0x80/0xa0 kernel/notifier.c:325
 [<0000000076485485>] profile_task_exit+0x1f/0x30 kernel/profile.c:140
 [<000000001268c73e>] do_exit+0x90/0x2aa0 kernel/exit.c:744
 [<0000000090bdd26e>] do_group_exit+0x111/0x300 kernel/exit.c:945
 [<00000000db2ee705>] SYSC_exit_group kernel/exit.c:956 [inline]
 [<00000000db2ee705>] SyS_exit_group+0x1d/0x20 kernel/exit.c:954
 [<000000006353c106>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<000000005cc3fd54>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<000000001ff07dbc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<000000001ff07dbc>] watchdog+0x13c/0xae0 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<00000000e1289144>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
1 lock held by rsyslogd/1904:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<00000000e0db514b>] __fdget_pos+0xa8/0xd0 fs/file.c:782
2 locks held by getty/2031:
 #0:  (&tty->ldisc_sem){++++++}, at: [<00000000151c0bae>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<0000000006f72859>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by getty/2167:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by getty/2168:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by getty/2169:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by getty/2170:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by getty/2171:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by getty/2172:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4348:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4344:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4349:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4347:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4352:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4350:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4351:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4353:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by syz-executor371/4354:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325
1 lock held by run-parts/4357:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<00000000ab0a6b74>] blocking_notifier_call_chain+0x6a/0xa0 kernel/notifier.c:325

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.169+ #42
 ffff8801d98d7cc8 ffffffff81b4f7f1 0000000000000000 0000000000000000
 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5aa8c 0000000000000000 0000000000000000 0000000000000000
Call Trace:
 [<0000000035ad1dd1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000035ad1dd1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000ff11a093>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<0000000099f8dcb2>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<000000009293479e>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<000000009ba85733>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<000000009ba85733>] check_hung_task kernel/hung_task.c:125 [inline]
 [<000000009ba85733>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<000000009ba85733>] watchdog+0x661/0xae0 kernel/hung_task.c:239
 [<000000006ebf7f29>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000a4138843>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff828105a2