INFO: task login:8494 blocked for more than 140 seconds. Not tainted 4.19.89-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D26864 8494 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+0x17bb/0x3080 kernel/exit.c:874 do_group_exit+0x135/0x370 kernel/exit.c:979 __do_sys_exit_group kernel/exit.c:990 [inline] __se_sys_exit_group kernel/exit.c:988 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:988 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f7e773b81e8 Code: Bad RIP value. RSP: 002b:00007ffd94157a28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7e773b81e8 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00007f7e7768d840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007f7e77693740 R11: 0000000000000246 R12: 00007f7e7768d840 R13: 0000000000000001 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 1 lock held by khungtaskd/1068: #0: 00000000f3904d64 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438 1 lock held by rsyslogd/7607: #0: 00000000eb8b3d80 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767 2 locks held by getty/7729: #0: 00000000b5a25525 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000c1a34b7c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7730: #0: 0000000049eef447 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000007e3c8ad3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7731: #0: 00000000c30d3256 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000048ce2b7e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7732: #0: 000000009af7d17b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000003a72cfb5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7733: #0: 00000000ced2043f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000da58461a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/7734: #0: 000000006b052a28 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000003f8211d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by login/8494: #0: 000000002910e040 (&tty->legacy_mutex){+.+.}, at: tty_lock+0x73/0xb0 drivers/tty/tty_mutex.c:19 #1: 00000000187de1fd (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:388 3 locks held by syz-executor922/8558: #0: 00000000187de1fd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000974b9730 (&buf->lock){+.+.}, at: tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 #2: 0000000019361f4a (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1817 [inline] #2: 0000000019361f4a (&rq->lock){-.-.}, at: __schedule+0x1f8/0x1dc0 kernel/sched/core.c:3453 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1068 Comm: khungtaskd Not tainted 4.19.89-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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8558 Comm: syz-executor922 Not tainted 4.19.89-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rcu_lockdep_current_cpu_online kernel/rcu/tree.c:1078 [inline] RIP: 0010:rcu_lockdep_current_cpu_online+0xcb/0x1c0 kernel/rcu/tree.c:1068 Code: 20 00 0f 85 cf 00 00 00 49 8b 9d d8 12 00 00 e8 bb 6f 09 02 89 c0 48 8d 3c c5 00 bf bd 88 48 89 fa 48 c1 ea 03 42 80 3c 22 00 <0f> 85 b1 00 00 00 48 03 1c c5 00 bf bd 88 48 8d 7b 20 48 89 f8 48 RSP: 0018:ffff88809149f668 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 000000000002d000 RCX: ffffffff836274ca RDX: 1ffffffff117b7e0 RSI: ffffffff836274d8 RDI: ffffffff88bdbf00 RBP: ffff88809149f690 R08: ffff8880aa3fa2c0 R09: ffffed1015d04733 R10: ffffed1015d04732 R11: ffff8880ae823993 R12: dffffc0000000000 R13: ffffffff88f99600 R14: ffff8880aa3fa2c0 R15: 0000000000000f9e FS: 0000000000b53880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000090066000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_lock_held+0x8a/0xd0 kernel/rcu/update.c:285 task_css_set include/linux/cgroup.h:469 [inline] task_dfl_cgroup include/linux/cgroup.h:538 [inline] cgroup_account_cputime include/linux/cgroup.h:769 [inline] update_curr+0x65e/0x8a0 kernel/sched/fair.c:829 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: 0033:0x441219 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:00007ffe87049328 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441219 RDX: 00000000200001c0 RSI: 000000000000541c RDI: 0000000000000003 RBP: 00000000000a20d5 R08: 000000000000000d R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402040 R13: 00000000004020d0 R14: 0000000000000000 R15: 0000000000000000