Dropped {multi|broad}cast of type= [86dd] INFO: task kworker/u4:2:38 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:2 D26144 38 2 0x80000000 Workqueue: events_unbound flush_to_ldisc 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 flush_to_ldisc+0x39/0x400 drivers/tty/tty_buffer.c:499 process_one_work+0x863/0x1600 kernel/workqueue.c:2114 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task login:7374 blocked for more than 140 seconds. Not tainted 4.14.170-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D25920 7374 1 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_timeout+0x93b/0xe10 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144 flush_work+0x3eb/0x730 kernel/workqueue.c:2891 tty_buffer_flush_work+0x16/0x20 drivers/tty/tty_buffer.c:612 n_tty_read+0x813/0x17d0 drivers/tty/n_tty.c:2199 tty_read+0x171/0x270 drivers/tty/tty_io.c:866 __vfs_read+0x105/0x6a0 fs/read_write.c:411 vfs_read+0x137/0x350 fs/read_write.c:447 SYSC_read fs/read_write.c:574 [inline] SyS_read+0xfd/0x230 fs/read_write.c:567 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f5db6fae310 RSP: 002b:00007fff583c8698 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5db6fae310 RDX: 00000000000001ff RSI: 00007fff583c8900 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f5db7891700 R09: 0000000000000000 R10: 00007fff583c8650 R11: 0000000000000246 R12: 00007fff583c8900 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 3 locks held by kworker/u4:2/38: #0: ("events_unbound"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events_unbound"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events_unbound"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events_unbound"){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&buf->work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 #2: (&buf->lock){+.+.}, at: [] flush_to_ldisc+0x39/0x400 drivers/tty/tty_buffer.c:499 1 lock held by khungtaskd/1053: #0: (tasklist_lock){.+.?}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 2 locks held by login/7374: #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/7375: #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/7376: #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/7377: #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/7378: #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/7379: #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/7380: #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.1/5715: #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: 1053 Comm: khungtaskd Not tainted 4.14.170-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: 5715 Comm: syz-executor.1 Not tainted 4.14.170-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff888064f66540 task.stack: ffff88820af50000 RIP: 0010:match_held_lock+0x2a/0x5f0 kernel/locking/lockdep.c:3554 RSP: 0018:ffff88820af57698 EFLAGS: 00000806 RAX: dffffc0000000000 RBX: ffff888064f66540 RCX: ffff888064f66dc0 RDX: ffffed10415eaeca RSI: ffffffff87f84ee0 RDI: ffff888064f66dc0 RBP: ffff88820af576b8 R08: 0000000000000000 R09: ffff888064f66e58 R10: ffff888064f66e38 R11: ffff888064f66540 R12: ffffffff87f84ee0 R13: 1ffff110415eaeca R14: ffffffff87f84ee0 R15: ffff88820af57690 FS: 00007f61f8a75700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c429117000 CR3: 000000006e0d3000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: __lock_is_held+0xb6/0x140 kernel/locking/lockdep.c:3814 lock_is_held_type+0x110/0x210 kernel/locking/lockdep.c:4032 lock_is_held include/linux/lockdep.h:437 [inline] rcu_read_lock_held kernel/rcu/update.c:332 [inline] rcu_read_lock_held+0xa3/0xd0 kernel/rcu/update.c:324 task_css include/linux/cgroup.h:481 [inline] task_ca kernel/sched/cpuacct.c:54 [inline] cpuacct_charge+0x2d1/0x360 kernel/sched/cpuacct.c:360 update_curr+0x2d9/0x6a0 kernel/sched/fair.c:856 pick_next_task_fair+0x661/0x1430 kernel/sched/fair.c:6303 pick_next_task kernel/sched/core.c:3232 [inline] __schedule+0x43e/0x1cd0 kernel/sched/core.c:3357 schedule+0x92/0x1c0 kernel/sched/core.c:3428 paste_selection+0x293/0x3f2 drivers/tty/vt/selection.c:355 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: 0033:0x45b3b9 RSP: 002b:00007f61f8a74c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f61f8a756d4 RCX: 000000000045b3b9 RDX: 0000000020000000 RSI: 000000000000541c RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000056c R14: 00000000004c6b63 R15: 000000000075bf2c Code: 00 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 41 57 41 56 4c 8d 7d d8 49 89 f6 41 55 4c 8d 6d 98 49 c1 ed 03 41 54 49 8d 54 05 00 <53> 48 89 fb 48 83 c7 10 48 83 ec 50 48 c7 45 98 b3 8a b5 41 48