device lo entered promiscuous mode device lo entered promiscuous mode INFO: task kworker/u4:3:32436 blocked for more than 120 seconds. Not tainted 4.9.98-g63a812b #17 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:3 D27240 32436 2 0x00000000 Workqueue: events_unbound flush_to_ldisc ffff8801d3cd0000 0000000000000000 ffff8801ca47cfc0 ffff8801d93dc800 ffff8801db221b98 ffff8801d7f7f8c8 ffffffff839e377d ffff8801d3cd08c8 ffffed003a79a118 ffff8801d3cd0000 00fffc0000000000 ffff8801db222468 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3557 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621 [] commit_echoes+0x120/0x1b0 drivers/tty/n_tty.c:764 [] n_tty_receive_char_fast drivers/tty/n_tty.c:1418 [inline] [] n_tty_receive_buf_fast drivers/tty/n_tty.c:1578 [inline] [] __receive_buf drivers/tty/n_tty.c:1613 [inline] [] n_tty_receive_buf_common+0x1878/0x2300 drivers/tty/n_tty.c:1711 [] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746 [] tty_ldisc_receive_buf+0xaf/0x190 drivers/tty/tty_buffer.c:455 [] receive_buf drivers/tty/tty_buffer.c:474 [inline] [] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533 [] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092 [] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Showing all locks held in the system: 2 locks held by khungtaskd/520: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 2 locks held by getty/3768: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133 6 locks held by kworker/u4:3/32436: #0: ("events_unbound"){.+.+.+}, at: [] work_static include/linux/workqueue.h:186 [inline] #0: ("events_unbound"){.+.+.+}, at: [] set_work_data kernel/workqueue.c:617 [inline] #0: ("events_unbound"){.+.+.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ("events_unbound"){.+.+.+}, at: [] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085 #1: ((&buf->work)){+.+...}, at: [] process_one_work+0x728/0x1500 kernel/workqueue.c:2089 #2: (&tty->ldisc_sem){++++++}, at: [] tty_ldisc_ref+0x20/0x80 drivers/tty/tty_ldisc.c:296 #3: (&port->buf.lock/1){+.+...}, at: [] flush_to_ldisc+0x86/0x370 drivers/tty/tty_buffer.c:505 #4: (&o_tty->termios_rwsem/1){++++..}, at: [] n_tty_receive_buf_common+0x8b/0x2300 drivers/tty/n_tty.c:1674 #5: (&ldata->output_lock){+.+...}, at: [] commit_echoes+0x120/0x1b0 drivers/tty/n_tty.c:764 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 520 Comm: khungtaskd Not tainted 4.9.98-g63a812b #17 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d86d7d08 ffffffff81eb0e89 0000000000000000 0000000000000000 0000000000000000 0000000000000001 ffffffff810b7da0 ffff8801d86d7d40 ffffffff81ebc187 0000000000000000 0000000000000000 0000000000000003 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6b4/0xa20 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5616 Comm: syz-executor3 Not tainted 4.9.98-g63a812b #17 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801cc863000 task.stack: ffff8801d5328000 RIP: 0010:[] c [] __read_once_size include/linux/compiler.h:243 [inline] RIP: 0010:[] c [] __sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:105 RSP: 0018:ffff8801d532f970 EFLAGS: 00000246 RAX: 0000000000040000 RBX: ffffc9000e549000 RCX: ffffc900103af000 RDX: 000000000003ffff RSI: ffffffff82118a5f RDI: ffffc9000e54a676 RBP: ffff8801d532f970 R08: ffff8801cc863938 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000009f6a71417 R13: 0000000000000267 R14: dffffc0000000000 R15: 00000009f6a71417 FS: 00007f6e525fa700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6cc00af000 CR3: 00000001cf628000 CR4: 00000000001606f0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Stack: ffff8801d532f9e8c ffffffff82118a5fc ffff8801d532f9c0c 0000000000000000c ffffc9000e54b278c ffffed0030ee5185c ffff880187728c2cc ffffc9000e549020c 0000000000001f00c ffff880187728880c ffffc9000e54b300c ffffc9000e549000c Call Trace: [] echo_buf drivers/tty/n_tty.c:146 [inline] [] __process_echoes+0x5cf/0x780 drivers/tty/n_tty.c:734 [] flush_echoes drivers/tty/n_tty.c:801 [inline] [] __receive_buf drivers/tty/n_tty.c:1617 [inline] [] n_tty_receive_buf_common+0xd34/0x2300 drivers/tty/n_tty.c:1711 [] n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1740 [] tiocsti drivers/tty/tty_io.c:2314 [inline] [] tty_ioctl+0xc8f/0x2270 drivers/tty/tty_io.c:2905 [] vfs_ioctl fs/ioctl.c:43 [inline] [] file_ioctl fs/ioctl.c:493 [inline] [] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677 [] SYSC_ioctl fs/ioctl.c:694 [inline] [] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: cbc cb2 ccb c7e c81 ce2 c00 c01 c1f c00 c48 c8b c75 c08 c75 c2b c8b c90 c80 c12 c00 c00 c83 cfa c02 c75 c20 c48 c8b c88 c88 c12 c00 c00 c8b c80 c84 c12 c00 c00 c48 c8b c11 c<48> c83 cc2 c01 c48 c39 cd0 c76 c07 c48 c89 c34 cd1 c48 c89 c11 c5d cc3 c0f c1f c00 c