watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [kworker/u4:5:6859] Modules linked in: irq event stamp: 1468184 hardirqs last enabled at (1468183): [] restore_regs_and_return_to_kernel+0x0/0x2b hardirqs last disabled at (1468184): [] interrupt_entry+0xb5/0xf0 arch/x86/entry/entry_64.S:625 softirqs last enabled at (1427896): [] __do_softirq+0x778/0xaf5 kernel/softirq.c:311 softirqs last disabled at (1427833): [] invoke_softirq kernel/softirq.c:365 [inline] softirqs last disabled at (1427833): [] irq_exit+0x1d1/0x200 kernel/softirq.c:405 CPU: 0 PID: 6859 Comm: kworker/u4:5 Not tainted 4.17.0-rc5+ #57 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound flush_to_ldisc RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x4/0x20 kernel/kcov.c:194 RSP: 0018:ffff8801b53e7258 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13 RAX: ffff8801b3db0140 RBX: 000000006f58bcda RCX: ffffffff8397b33c RDX: ffffffff90a7446b RSI: ffffffff90a7446b RDI: 0000000000000edf RBP: ffff8801b53e72d0 R08: ffff8801b3db0140 R09: 0000000000000006 R10: ffff8801b3db0140 R11: 0000000000000000 R12: ffffc90001c21000 R13: 0000000000000145 R14: ffffffff90a7446b R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc96290438 CR3: 00000001d022f000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 000000000000629f DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: commit_echoes+0x163/0x1d0 drivers/tty/n_tty.c:764 n_tty_receive_char_fast drivers/tty/n_tty.c:1416 [inline] n_tty_receive_buf_fast drivers/tty/n_tty.c:1576 [inline] __receive_buf drivers/tty/n_tty.c:1611 [inline] n_tty_receive_buf_common+0x2048/0x2c50 drivers/tty/n_tty.c:1709 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1744 tty_ldisc_receive_buf+0xb0/0x190 drivers/tty/tty_buffer.c:456 tty_port_default_receive_buf+0x110/0x170 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:475 [inline] flush_to_ldisc+0x3e9/0x560 drivers/tty/tty_buffer.c:524 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Code: c3 66 0f 1f 44 00 00 55 89 f2 89 fe bf 05 00 00 00 48 89 e5 48 8b 4d 08 e8 6a fe ff ff 5d c3 0f 1f 84 00 00 00 00 00 55 48 89 f2 <48> 89 fe bf 07 00 00 00 48 89 e5 48 8b 4d 08 e8 48 fe ff ff 5d Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54