INFO: task syz.6.614:9209 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.614 state:D stack:25096 pid:9209 tgid:9205 ppid:7486 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5584 [inline] __schedule+0x1828/0x58c0 kernel/sched/core.c:7389 __schedule_loop kernel/sched/core.c:7466 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7481 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7538 __mutex_lock_common kernel/locking/mutex.c:726 [inline] __mutex_lock+0x7c4/0x15a0 kernel/locking/mutex.c:821 sync_bdevs+0x294/0x480 block/bdev.c:1378 ksys_sync fs/sync.c:105 [inline] __ia32_sys_sync+0xc5/0x120 fs/sync.c:111 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x16a/0x530 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc540da94d9 RSP: 002b:00007fc541c9d028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 00007fc541025fa0 RCX: 00007fc540da94d9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fc541025fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc541026038 R14: 00007fc541025fa0 R15: 00007ffe95d609d8 Showing all locks held in the system: locks held by kworker/0:1/11: 2, on CPU#0: #0: ffff88813fe0dd48 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813fe0dd48 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813fe0dd48 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88813fe0dd48 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90000107c40 ((gc_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90000107c40 ((gc_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90000107c40 ((gc_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90000107c40 ((gc_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 locks held by kworker/u8:1/14: 3, on CPU#0: #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90000137c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90000137c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90000137c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90000137c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffff888026fa1258 (&devlink->lock_key#10 ){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xb30 drivers/net/netdevsim/dev.c:834 locks held by kworker/u8:2/32: 3, on CPU#0: #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90000a87c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90000a87c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90000a87c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90000a87c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffff8880502e0800 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6990 [inline] #2: ffff8880502e0800 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x420 net/wireless/core.c:595 locks held by pr/ttyS0/33: 1, on CPU#0: #0: ffffffff90033d78 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline] #0: ffffffff90033d78 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:529 [inline] #0: ffffffff90033d78 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291 locks held by khungtaskd/34: 1, on CPU#0: #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871 locks held by kworker/u8:4/62: 3, on CPU#0: #0: ffff888041a08148 ((wq_completion)wg-kex-wg1#19){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff888041a08148 ((wq_completion)wg-kex-wg1#19){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff888041a08148 ((wq_completion)wg-kex-wg1#19){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff888041a08148 ((wq_completion)wg-kex-wg1#19){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc9000203fc40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9000203fc40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9000203fc40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc9000203fc40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #2: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #2: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline] #2: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495 locks held by kworker/u8:6/739: 3, on CPU#0: #0: ffff8880b823c5e0 ( &rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb2/0x160 kernel/sched/core.c:685 #1: ffff8880b8224708 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x57/0x7d0 kernel/sched/psi.c:928 #2: ffff8880b823c5e0 (&rq->__lock){-.-.}-{2:2}, at: finish_lock_switch kernel/sched/core.c:5312 [inline] #2: ffff8880b823c5e0 (&rq->__lock){-.-.}-{2:2}, at: finish_task_switch+0x159/0xc60 kernel/sched/core.c:5433 locks held by klogd/4983: 1, on CPU#1: #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline] #0: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495 locks held by getty/5384: 2, last CPU#0: #0: ffff8880366ea0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000322e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by syz-executor/5616: 2, on CPU#1: #0: ffff88802d676c60 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1717 [inline] #0: ffff88802d676c60 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x21/0x50 net/ipv4/tcp.c:1464 #1: ffffffff902b1cd0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:249 [inline] #1: ffffffff902b1cd0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60 include/linux/srcu.h:356 locks held by kworker/u8:9/5835: 6, on CPU#1: #0: ffff88801d686148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801d686148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801d686148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88801d686148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc9000552fc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9000552fc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9000552fc40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc9000552fc40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff916855c8 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:684 #3: ffff8880772ab128 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1109 [inline] #3: ffff8880772ab128 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:124 [inline] #3: ffff8880772ab128 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x122/0x560 net/devlink/core.c:581 #4: ffff8880772a8258 (&devlink->lock_key#18){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:314 [inline] #4: ffff8880772a8258 (&devlink->lock_key#18){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:125 [inline] #4: ffff8880772a8258 (&devlink->lock_key#18){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x138/0x560 net/devlink/core.c:581 #5: ffffffff901608e8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline] #5: ffffffff901608e8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x388/0x760 kernel/rcu/tree_exp.h:966 locks held by syz-executor/6362: 1, on CPU#0: #0: ffff888079090478 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:531 locks held by kworker/u8:12/6883: 3, on CPU#1: #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc9000503fc40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: psi_task_switch+0x57/0x7d0 kernel/sched/psi.c:928 #2: ffff8880b8326498 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x904/0xed0 kernel/time/timer.c:1118 locks held by kworker/u8:13/7056: 2, on CPU#1: #0: ffff888033b6f148 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff888033b6f148 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff888033b6f148 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff888033b6f148 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90003067c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90003067c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90003067c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90003067c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 locks held by udevd/7434: 1, last CPU#0: #0: ffff888023773350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:990 locks held by syz.6.614/9209: 1, last CPU#0: #0: ffff888023773350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x294/0x480 block/bdev.c:1378 locks held by syz-executor/9355: 1, on CPU#1: #0: ffff888035f6c478 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:531 locks held by udevd/9471: 1, on CPU#1: #0: ffff8880790f7180 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_downgrade include/linux/mmap_lock.h:610 [inline] #0: ffff8880790f7180 (&mm->mmap_lock){++++}-{4:4}, at: vms_complete_munmap_vmas+0x23f/0xc10 mm/vma.c:1437 locks held by syz.3.728/9686: 1, last CPU#1: #0: ffff888023773350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x294/0x480 block/bdev.c:1378 locks held by syz-executor/10337: 4, on CPU#1: #0: ffffffff916855c8 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x529/0x780 net/core/net_namespace.c:585 #1: ffffffff913e5ec8 (devices_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x1fb/0x2f0 drivers/infiniband/core/device.c:1221 #2: ffffffff913e6088 (rdma_nets_rwsem){++++}-{4:4}, at: rdma_dev_init_net+0x233/0x2f0 drivers/infiniband/core/device.c:1226 #3: ffff88807dda5020 (&device->compat_devs_mutex){+.+.}-{4:4}, at: add_one_compat_dev+0xf0/0x640 drivers/infiniband/core/device.c:976 locks held by syz.2.875/10424: 1, last CPU#0: #0: ffffffff915ef660 (register_mutex#4){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff915ef660 (register_mutex#4){+.+.}-{4:4}, at: odev_release+0x4b/0x70 sound/core/seq/oss/seq_oss.c:143 locks held by syz.2.875/10427: 1, last CPU#1: #0: ffff88803364f960 (&rmidi->open_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffff88803364f960 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_release+0x76/0x220 sound/core/rawmidi.c:665 locks held by syz.9.876/10431: 2, on CPU#1: #0: ffff88807f7e8340 (&mm->mmap_lock){++++}-{4:4} , at: mmap_read_lock include/linux/mmap_lock.h:616 [inline] , at: exit_mmap+0x19c/0xa40 mm/mmap.c:1299 #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:302 locks held by dhcpcd-run-hook/10432: 2, on CPU#0: #0: ffff88807f7ee540 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:548 [inline] #0: ffff88807f7ee540 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x2d5/0xa40 mm/mmap.c:1323 #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline] #1: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:377 [inline] watchdog+0x1073/0x10f0 kernel/hung_task.c:598 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 33 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:425 Code: e8 9e b2 42 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 2f 4c ba fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 95 d2 89 fb cc 44 89 f9 80 e1 07 RSP: 0018:ffffc90000a978b8 EFLAGS: 00000002 RAX: 1ffffffff3841500 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020 RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff85866df0 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffffff9c20aee0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888123404000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055557cb24a38 CR3: 0000000023b6e000 CR4: 0000000000350ef0 Call Trace: serial_in drivers/tty/serial/8250/8250.h:134 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:156 [inline] wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2036 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3294 [inline] __serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3369 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3402 [inline] __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3456 [inline] serial8250_console_write+0xa7e/0x1200 drivers/tty/serial/8250/8250_port.c:3520 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline] nbcon_kthread_func+0x6d9/0x8d0 kernel/printk/nbcon.c:1271 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245