INFO: task login:10409 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 10409 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: 0033:0x7fada16df1e8 Code: Bad RIP value. RSP: 002b:00007ffc09aee828 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fada16df1e8 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00007fada19b4840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007fada19ba740 R11: 0000000000000246 R12: 00007fada19b4840 R13: 0000000000000001 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 1 lock held by khungtaskd/1115: #0: ffffffff899a5680 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 3 locks held by rs:main Q:Reg/9915: #0: ffff8880ae937358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline] #0: ffff8880ae937358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f90 kernel/sched/core.c:4029 #1: ffff8882149b2428 (sb_writers#4){.+.+}, at: file_start_write include/linux/fs.h:2885 [inline] #1: ffff8882149b2428 (sb_writers#4){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 #2: ffff8880989c57c8 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_lock include/linux/fs.h:791 [inline] #2: ffff8880989c57c8 (&sb->s_type->i_mutex_key#10){+.+.}, at: ext4_buffered_write_iter+0xba/0x460 fs/ext4/file.c:246 1 lock held by rsyslogd/9917: #0: ffff888092c83ba0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/10040: #0: ffff8880a356d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018532e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10041: #0: ffff88809f899090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017c32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10042: #0: ffff888088459090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018232e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10043: #0: ffff8880a2afc090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018432e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10044: #0: ffff88809f129090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018332e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10045: #0: ffff888099fbb090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900011302e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by login/10409: #0: ffff8880a3bc8198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19 #1: ffff8880a3bc8090 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 2 locks held by syz-executor491/10498: #0: ffff8880a3bc8090 (&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 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1115 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 10498 Comm: syz-executor491 Not tainted 5.5.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline] RIP: 0010:lock_is_held_type+0x272/0x320 kernel/locking/lockdep.c:4524 Code: ff df c7 83 94 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 88 00 00 00 48 83 3d be ca 38 08 00 74 31 48 8b 7d c0 57 9d <0f> 1f 44 00 00 48 83 c4 20 44 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d RSP: 0018:ffffc90003107668 EFLAGS: 00000086 RAX: 1ffffffff132669b RBX: ffff8880a90b61c0 RCX: ffff8880a90b6a58 RDX: dffffc0000000000 RSI: ffffffff899c8380 RDI: 0000000000000086 RBP: ffffc900031076b0 R08: 1ffff11015d2703c R09: ffffed1015d2703d R10: ffffed1015d2703c R11: ffff8880ae9381e3 R12: 0000000000000000 R13: ffff8880a90b6ad0 R14: ffffffff899c8380 R15: 0000000000000004 FS: 00000000010b1880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006cc080 CR3: 000000009f232000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_is_held include/linux/lockdep.h:361 [inline] task_css include/linux/cgroup.h:491 [inline] task_ca kernel/sched/cpuacct.c:43 [inline] cpuacct_charge+0x26e/0x360 kernel/sched/cpuacct.c:349 cgroup_account_cputime include/linux/cgroup.h:773 [inline] update_curr+0x2f5/0x8d0 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:00007ffdd3075288 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441219 RDX: 0000000020000040 RSI: 000000000000541c RDI: 0000000000000003 RBP: 00000000000afb69 R08: 000000000000000d R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402040 R13: 00000000004020d0 R14: 0000000000000000 R15: 0000000000000000