INFO: task login:8982 blocked for more than 143 seconds. Not tainted 5.5.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D23224 8982 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: 0033:0x7f489a9441e8 Code: Bad RIP value. RSP: 002b:00007ffc539294a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f489a9441e8 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00007f489ac19840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007f489ac1f740 R11: 0000000000000246 R12: 00007f489ac19840 R13: 0000000000000001 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 1 lock held by khungtaskd/1117: #0: ffffffff899a56c0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/8892: #0: ffff8880942438a0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by login/8982: #0: ffff88808afac198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19 #1: ffff88808afac090 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 2 locks held by getty/8983: #0: ffff888092c63090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8984: #0: ffff88809426d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8985: #0: ffff8880a8de4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000182b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8986: #0: ffff8880a85d4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000181b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8987: #0: ffff88808c78e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000180b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8988: #0: ffff88809a017090 (&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 3 locks held by syz-executor520/9189: #0: ffff88808afac090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffff8880aa5bc0a8 (&buf->lock){+.+.}, at: tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 #2: ffff8880ae837358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline] #2: ffff8880ae837358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f90 kernel/sched/core.c:4029 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1117 Comm: khungtaskd Not tainted 5.5.0-rc1-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: 9189 Comm: syz-executor520 Not tainted 5.5.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rcu_dynticks_curr_cpu_in_eqs+0x32/0xb0 kernel/rcu/tree.c:299 Code: c7 c3 00 81 03 00 48 83 ec 08 e8 79 34 30 02 48 ba 00 00 00 00 00 fc ff df 89 c0 48 8d 3c c5 60 81 55 89 48 89 f9 48 c1 e9 03 <80> 3c 11 00 75 63 48 03 1c c5 60 81 55 89 be 04 00 00 00 4c 8d a3 RSP: 0018:ffffc900028676c8 EFLAGS: 00000802 RAX: 0000000000000000 RBX: 0000000000038100 RCX: 1ffffffff12ab02c RDX: dffffc0000000000 RSI: ffffffff8392e053 RDI: ffffffff89558160 RBP: ffffc900028676e0 R08: ffff88808a37c3c0 R09: ffffed1015d0703d R10: ffffed1015d0703c R11: ffff8880ae8381e3 R12: ffff8880ae8373c0 R13: ffffffff899c5cf0 R14: ffff88808a37c3c0 R15: 0000000000000d74 FS: 0000000001371880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a7952000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_is_watching+0x10/0x30 kernel/rcu/tree.c:922 rcu_read_unlock include/linux/rcupdate.h:667 [inline] cgroup_account_cputime include/linux/cgroup.h:779 [inline] update_curr+0x5f8/0x8d0 kernel/sched/fair.c:860 pick_next_task_fair+0x221/0xc70 kernel/sched/fair.c:6680 pick_next_task kernel/sched/core.c:3921 [inline] __schedule+0x375/0x1f90 kernel/sched/core.c:4051 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: 0033:0x441219 Code: e8 3c ad 02 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 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffe618000b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441219 RDX: 0000000020000080 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000008b001 R08: 000000000000000d R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402040 R13: 00000000004020d0 R14: 0000000000000000 R15: 0000000000000000