INFO: task login:9482 blocked for more than 143 seconds. Not tainted 5.5.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D27648 9482 1 0x80000002 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 down_write_failed drivers/tty/tty_ldsem.c:262 [inline] __ldsem_down_write_nested+0x3b2/0x8f0 drivers/tty/tty_ldsem.c:324 ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 __tty_ldisc_lock drivers/tty/tty_ldisc.c:315 [inline] tty_ldisc_lock+0x66/0xb0 drivers/tty/tty_ldisc.c:339 tty_ldisc_hangup+0x1c6/0x640 drivers/tty/tty_ldisc.c:745 __tty_hangup.part.0+0x2fb/0x750 drivers/tty/tty_io.c:625 __tty_hangup drivers/tty/tty_io.c:575 [inline] tty_vhangup_session+0x25/0x30 drivers/tty/tty_io.c:735 disassociate_ctty.part.0+0xb4/0x740 drivers/tty/tty_jobctrl.c:267 disassociate_ctty+0x81/0xa0 drivers/tty/tty_jobctrl.c:261 do_exit+0x1b42/0x2ef0 kernel/exit.c:795 do_group_exit+0x135/0x360 kernel/exit.c:895 __do_sys_exit_group kernel/exit.c:906 [inline] __se_sys_exit_group kernel/exit.c:904 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:904 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f535b3cd1e8 Code: Bad RIP value. RSP: 002b:00007ffc776e75a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f535b3cd1e8 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00007f535b6a2840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007f535b6a8740 R11: 0000000000000246 R12: 00007f535b6a2840 R13: 0000000000000001 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 1 lock held by khungtaskd/914: #0: ffffffff899a5680 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/9051: #0: ffff8880a937c860 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/9142: #0: ffff8880963e4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000178b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9143: #0: ffff8880a0b3c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9144: #0: ffff88809539e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000176b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9145: #0: ffff8880a2914090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000170b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9146: #0: ffff8880a781e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000179b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9147: #0: ffff88821481a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900011402e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by login/9482: #0: ffff8880a3846198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19 #1: ffff8880a3846090 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 2 locks held by syz-executor605/9574: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 914 Comm: khungtaskd Not tainted 5.5.0-rc2-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+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:205 [inline] watchdog+0xb11/0x10c0 kernel/hung_task.c:289 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 9574 Comm: syz-executor605 Not tainted 5.5.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rcu_lockdep_current_cpu_online+0x2b/0x130 kernel/rcu/tree.c:962 Code: 8b 15 d1 0f a0 7e 81 e2 00 00 10 00 b8 01 00 00 00 75 0a 8b 15 1a 8b 17 09 85 d2 75 01 c3 55 bf 01 00 00 00 48 89 e5 41 54 53 <48> 83 ec 08 e8 ec c1 ee ff e8 07 2d 31 02 48 c7 c3 00 81 03 00 48 RSP: 0018:ffffc90002c17688 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffffc90002c176e0 RCX: ffffffff8162ae44 RDX: 0000000000000001 RSI: 0000000000000004 RDI: 0000000000000001 RBP: ffffc90002c17698 R08: 1ffff11015d0703c R09: ffffed1015d0703d R10: ffffed1015d0703c R11: ffff8880ae8381e3 R12: ffff8880ae838115 R13: ffff8880a8bd8040 R14: ffff8880a8bd8040 R15: ffff8880ae837358 FS: 00000000022b1880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006d3080 CR3: 00000000a2c68000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_lock_held_common kernel/rcu/update.c:109 [inline] rcu_read_lock_held_common+0xbd/0x130 kernel/rcu/update.c:99 rcu_read_lock_sched_held+0x5b/0xd0 kernel/rcu/update.c:120 trace_rcu_utilization include/trace/events/rcu.h:27 [inline] trace_rcu_utilization include/trace/events/rcu.h:27 [inline] rcu_note_context_switch+0x108a/0x1910 kernel/rcu/tree_plugin.h:332 __schedule+0x22a/0x1f90 kernel/sched/core.c:4019 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 paste_selection+0x2f5/0x460 drivers/tty/vt/selection.c:367 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441a79 Code: e8 ec 03 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 1b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd3e475758 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441a79 RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000003 RBP: 00007ffd3e475780 R08: 000000000000000d R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000a874f R13: 0000000000000004 R14: 00007ffd3e4757b0 R15: 0000000000000000