INFO: task getty:7983 blocked for more than 140 seconds. Not tainted 4.19.96-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. getty D25096 7983 1 0x80000002 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x866/0x1dc0 kernel/sched/core.c:3515 schedule+0x92/0x1c0 kernel/sched/core.c:3559 schedule_timeout+0x8c8/0xfc0 kernel/time/timer.c:1782 down_write_failed drivers/tty/tty_ldsem.c:284 [inline] __ldsem_down_write_nested+0x3b3/0x8f0 drivers/tty/tty_ldsem.c:346 ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:388 __tty_ldisc_lock drivers/tty/tty_ldisc.c:320 [inline] tty_ldisc_lock+0x50/0x90 drivers/tty/tty_ldisc.c:344 tty_ldisc_hangup+0x1b9/0x630 drivers/tty/tty_ldisc.c:746 __tty_hangup.part.0+0x306/0x720 drivers/tty/tty_io.c:623 __tty_hangup drivers/tty/tty_io.c:573 [inline] tty_vhangup_session+0x25/0x30 drivers/tty/tty_io.c:733 disassociate_ctty.part.0+0xb4/0x6f0 drivers/tty/tty_jobctrl.c:267 disassociate_ctty+0x81/0xa0 drivers/tty/tty_jobctrl.c:261 do_exit+0x180e/0x30d0 kernel/exit.c:878 do_group_exit+0x135/0x370 kernel/exit.c:983 __do_sys_exit_group kernel/exit.c:994 [inline] __se_sys_exit_group kernel/exit.c:992 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:992 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fbb86f371e8 Code: Bad RIP value. RSP: 002b:00007ffe76257818 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fbb86f371e8 RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 RBP: 00007fbb8720c840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007fbb87212740 R11: 0000000000000246 R12: 00007fbb8720c840 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000 INFO: task kworker/u4:2:10556 blocked for more than 140 seconds. Not tainted 4.19.96-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:2 D25568 10556 2 0x80000000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x866/0x1dc0 kernel/sched/core.c:3515 schedule+0x92/0x1c0 kernel/sched/core.c:3559 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3617 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1300 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:500 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Showing all locks held in the system: 1 lock held by khungtaskd/1082: #0: 000000000c18e38c (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438 1 lock held by rsyslogd/7861: #0: 0000000036ea4fb9 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767 2 locks held by getty/7983: #0: 000000004889e39b (&tty->legacy_mutex){+.+.}, at: tty_lock+0x73/0xb0 drivers/tty/tty_mutex.c:19 #1: 00000000f374df2a (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:388 2 locks held by getty/7984: #0: 00000000bcd459d7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000f53d3a39 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7985: #0: 00000000253f4aff (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000003801f051 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7986: #0: 00000000f5d6209d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000000c670d0e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7987: #0: 00000000f269c49d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000aad8df0b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7988: #0: 00000000e96b5399 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000071bad24c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7989: #0: 0000000004720a10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000f197bf0f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 3 locks held by kworker/u4:2/10556: #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000e6a42dd9 ((wq_completion)"events_unbound"){+.+.}, at: process_one_work+0x87e/0x1750 kernel/workqueue.c:2124 #1: 00000000144d2e7e ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x8b4/0x1750 kernel/workqueue.c:2128 #2: 0000000087db4213 (&buf->lock){+.+.}, at: flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:500 2 locks held by syz-executor.4/26374: #0: 00000000f374df2a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000087db4213 (&buf->lock){+.+.}, at: tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1082 Comm: khungtaskd Not tainted 4.19.96-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x9df/0xee0 kernel/hung_task.c:287 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 26374 Comm: syz-executor.4 Not tainted 4.19.96-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:match_held_lock+0x63/0x500 kernel/locking/lockdep.c:3475 Code: fd 01 00 00 48 8d 7b 22 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 <84> d2 0f 85 85 03 00 00 66 f7 43 22 f0 ff 0f 84 b2 01 00 00 48 8d RSP: 0018:ffff8880720575d8 EFLAGS: 00000006 RAX: 0000000000000003 RBX: ffff888097f4a8c0 RCX: ffff888097f4a8c0 RDX: 0000000000000000 RSI: ffffffff88f95ba0 RDI: ffff888097f4a8e2 RBP: ffff888072057608 R08: ffff888097f4a040 R09: ffffed1015d24733 R10: ffffed1015d24732 R11: ffff8880ae923993 R12: ffffffff88f95ba0 R13: ffffed1012fe9517 R14: 0000000000000000 R15: ffff888097f4a8c0 FS: 00007f63687cc700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000095114000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lock_is_held+0xb6/0x140 kernel/locking/lockdep.c:3723 lock_is_held_type+0x110/0x210 kernel/locking/lockdep.c:3941 lock_is_held include/linux/lockdep.h:344 [inline] rcu_read_lock_sched_held+0x110/0x130 kernel/rcu/update.c:118 trace_sched_stat_runtime include/trace/events/sched.h:428 [inline] update_curr+0x73b/0x8a0 kernel/sched/fair.c:828 pick_next_task_fair+0x6bf/0x1580 kernel/sched/fair.c:6698 pick_next_task kernel/sched/core.c:3361 [inline] __schedule+0x456/0x1dc0 kernel/sched/core.c:3489 schedule+0x92/0x1c0 kernel/sched/core.c:3559 paste_selection+0x2e8/0x443 drivers/tty/vt/selection.c:354 tioclinux+0x133/0x470 drivers/tty/vt/vt.c:3019 vt_ioctl+0x19ab/0x2530 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45af49 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f63687cbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49 RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f63687cc6d4 R13: 00000000004c6498 R14: 00000000004ddd98 R15: 00000000ffffffff