INFO: task getty:6946 blocked for more than 140 seconds. Not tainted 4.14.159-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. getty D25920 6946 1 0x80000002 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723 down_write_failed drivers/tty/tty_ldsem.c:298 [inline] __ldsem_down_write_nested+0x304/0x7b0 drivers/tty/tty_ldsem.c:360 ldsem_down_write+0x33/0x39 drivers/tty/tty_ldsem.c:402 __tty_ldisc_lock drivers/tty/tty_ldisc.c:332 [inline] tty_ldisc_lock+0x50/0x80 drivers/tty/tty_ldisc.c:356 tty_ldisc_hangup+0x1a6/0x5e0 drivers/tty/tty_ldisc.c:758 __tty_hangup.part.0+0x2d3/0x6d0 drivers/tty/tty_io.c:622 __tty_hangup drivers/tty/tty_io.c:572 [inline] tty_vhangup_session+0x25/0x30 drivers/tty/tty_io.c:732 disassociate_ctty.part.0+0x9b/0x6c0 drivers/tty/tty_jobctrl.c:266 disassociate_ctty+0x78/0x90 drivers/tty/tty_jobctrl.c:260 do_exit+0x1799/0x2c80 kernel/exit.c:852 do_group_exit+0x111/0x330 kernel/exit.c:951 SYSC_exit_group kernel/exit.c:962 [inline] SyS_exit_group+0x1d/0x20 kernel/exit.c:960 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7ffaf38f51e8 RSP: 002b:00007fff1218eda8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007ffaf38f51e8 RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 RBP: 00007ffaf3bca840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007ffaf3bd0740 R11: 0000000000000246 R12: 00007ffaf3bca840 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000 INFO: task syz-executor.5:18367 blocked for more than 140 seconds. Not tainted 4.14.159-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29224 18367 6995 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 tty_buffer_lock_exclusive+0x1f/0x30 drivers/tty/tty_buffer.c:60 paste_selection+0x106/0x3f2 drivers/tty/vt/selection.c:349 tioclinux+0x10e/0x400 drivers/tty/vt/vt.c:2696 vt_ioctl+0x180c/0x2170 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x841/0x1320 drivers/tty/tty_io.c:2661 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a919 RSP: 002b:00007f577c9fac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919 RDX: 0000000020000080 RSI: 000000000000541c RDI: 0000000000000003 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f577c9fb6d4 R13: 00000000004c5c62 R14: 00000000004dbf18 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1044: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 2 locks held by getty/6946: #0: (&tty->legacy_mutex){+.+.}, at: [] tty_lock+0x68/0x80 drivers/tty/tty_mutex.c:19 #1: (&tty->ldisc_sem){++++}, at: [] ldsem_down_write+0x33/0x39 drivers/tty/tty_ldsem.c:402 2 locks held by getty/6947: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/6949: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/6950: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/6951: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/6952: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/10055: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/18367: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&buf->lock){+.+.}, at: [] tty_buffer_lock_exclusive+0x1f/0x30 drivers/tty/tty_buffer.c:60 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1044 Comm: khungtaskd Not tainted 4.14.159-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 18352 Comm: syz-executor.5 Not tainted 4.14.159-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff88820fd70000 task.stack: ffff888201788000 RIP: 0010:lookup_object lib/debugobjects.c:132 [inline] RIP: 0010:debug_object_activate+0x178/0x450 lib/debugobjects.c:436 RSP: 0018:ffff8880aed07be0 EFLAGS: 00000046 RAX: 1ffff11011cf00ea RBX: 000000000000000e RCX: 00000000c6481566 RDX: dffffc0000000000 RSI: ffff88820fd708f8 RDI: ffff88808e780750 RBP: ffff8880aed07ca8 R08: 00000000000030f3 R09: ffffffff89c41968 R10: 0000000000000082 R11: ffff88820fd70000 R12: ffff88808e780738 R13: ffff88805a986808 R14: 1ffff11015da0f80 R15: ffffffff87f5a3c0 FS: 00007f577ca1c700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c432ca9480 CR3: 000000008f5a5000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: debug_work_activate kernel/workqueue.c:493 [inline] __queue_work+0x7a/0xf30 kernel/workqueue.c:1382 delayed_work_timer_fn+0x6e/0x90 kernel/workqueue.c:1502 call_timer_fn+0x161/0x670 kernel/time/timer.c:1279 expire_timers kernel/time/timer.c:1314 [inline] __run_timers kernel/time/timer.c:1636 [inline] __run_timers kernel/time/timer.c:1604 [inline] run_timer_softirq+0x3c9/0x1520 kernel/time/timer.c:1649 __do_softirq+0x244/0x9a0 kernel/softirq.c:288 invoke_softirq kernel/softirq.c:368 [inline] irq_exit+0x160/0x1b0 kernel/softirq.c:409 exiting_irq arch/x86/include/asm/apic.h:648 [inline] smp_apic_timer_interrupt+0x146/0x5e0 arch/x86/kernel/apic/apic.c:1102 apic_timer_interrupt+0x96/0xa0 arch/x86/entry/entry_64.S:792 RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:325 [inline] RIP: 0010:tty_throttled include/linux/tty.h:399 [inline] RIP: 0010:paste_selection+0x250/0x3f2 drivers/tty/vt/selection.c:354 RSP: 0018:ffff88820178f9c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: 0000000000000000 RBX: ffff88820178faa8 RCX: ffffc90007c33000 RDX: 0000000000040000 RSI: 1ffff11041fae272 RDI: ffff8880a038ce48 RBP: ffff88820178fad0 R08: ffff88820fd70000 R09: ffff88820fd708c8 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff88820fd70000 R14: ffff8880a038c9c0 R15: ffff8880565d0600 tioclinux+0x10e/0x400 drivers/tty/vt/vt.c:2696 vt_ioctl+0x180c/0x2170 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0x841/0x1320 drivers/tty/tty_io.c:2661 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a919 RSP: 002b:00007f577ca1bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919 RDX: 0000000020000080 RSI: 000000000000541c RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f577ca1c6d4 R13: 00000000004c5c62 R14: 00000000004dbf18 R15: 00000000ffffffff Code: 03 80 3c 10 00 0f 85 6a 02 00 00 4d 8b 24 24 4d 85 e4 0f 84 b4 00 00 00 49 8d 7c 24 18 83 c3 01 48 89 f8 48 c1 e8 03 80 3c 10 00 <0f> 85 1c 02 00 00 4d 3b 6c 24 18 75 c2 49 8d 5c 24 10 48 b8 00