INFO: task syz.0.1629:11021 blocked for more than 143 seconds. Tainted: G L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.1629 state:D stack:28920 pid:11021 tgid:11020 ppid:5617 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5402 [inline] __schedule+0x16f9/0x5500 kernel/sched/core.c:7204 __schedule_loop kernel/sched/core.c:7283 [inline] rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7579 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1666 __rt_mutex_slowlock kernel/locking/rtmutex.c:1743 [inline] __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1783 [inline] rt_mutex_slowlock+0x2dc/0x780 kernel/locking/rtmutex.c:1823 mutex_lo[ 644.776422][ T39] __rt_mutex_lock kernel/locking/rtmutex.c:1838 [inline] mutex_lo[ 644.776422][ T39] __mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline] mutex_lo[ 644.776422][ T39] mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578 epoll_mutex_lock fs/eventpoll.c:2512 [inline] ep_ctl_lock fs/eventpoll.c:2559 [inline] do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636 do_epoll_ctl fs/eventpoll.c:2698 [inline] __do_sys_epoll_ctl fs/eventpoll.c:2715 [inline] __se_sys_epoll_ctl+0x14e/0x210 fs/eventpoll.c:2706 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1fc826ce59 RSP: 002b:00007f1fc64c6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9 RAX: ffffffffffffffda RBX: 00007f1fc84e5fa0 RCX: 00007f1fc826ce59 RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000005 RBP: 00007f1fc8302d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000200000000080 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1fc84e6038 R14: 00007f1fc84e5fa0 R15: 00007ffffb9bc6d8 Showing all locks held in the system: 5 locks held by ktimers/0/16: #0: ffff8880b863b8a0 (&rq->__lock){-...}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:661 #1: ffff8880b8624500 (psi_seq){-...}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933 #2: ffff8880b8624168 (tasklet_sync_callback.cb_lock.lock.wait_lock){....}-{2:2}, at: rt_mutex_slowunlock+0xbf/0x8b0 kernel/locking/rtmutex.c:1430 #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #4: ffff888058dc1c50 (_T->lock){....}-{2:2}, at: rt_mutex_slowunlock+0xbf/0x8b0 kernel/locking/rtmutex.c:1430 4 locks held by pr/legacy/17: #0: ffffffff8e1bccc0 (console_lock){+.+.}-{0:0}, at: legacy_kthread_func+0x1a3/0x250 kernel/printk/printk.c:3711 #1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline] #1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline] #1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline] #1: ffffffff8e0a45b8 (console_srcu){....}-{0:0}, at: console_flush_one_record+0xfa/0xb90 kernel/printk/printk.c:3246 #2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:719 [inline] #2: ffffffff99e10018 (&port_lock_key){+.+.}-{3:3}, at: serial8250_console_write+0x178/0x1b50 drivers/tty/serial/8250/8250_port.c:3338 #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 1 lock held by khungtaskd/39: #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6777 6 locks held by kworker/u8:7/992: #0: ffff88813fe54138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293 #1: ffffc90005dc7c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294 #2: ffff88805f36e310 (&devlink->lock_key#12){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xbd0 drivers/net/netdevsim/dev.c:909 #3: ffff888036859d20 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #3: ffff888036859d20 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report drivers/net/netdevsim/dev.c:862 [inline] #3: ffff888036859d20 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report_work+0x1ad/0xbd0 drivers/net/netdevsim/dev.c:922 #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa6/0x2550 arch/x86/kernel/unwind_orc.c:495 1 lock held by udevd/4979: #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #0: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: path_init+0x12d/0x14d0 fs/namei.c:2685 2 locks held by getty/5367: #0: ffff8880358db0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90003cc62e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211 3 locks held by kworker/1:6/5821: #0: ffff888022e9a138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293 #1: ffffc900059bfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294 #2: ffff88802a9c6210 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline] #2: ffff88802a9c6210 (&dev->mutex){....}-{4:4}, at: hub_event+0x17c/0x4f60 drivers/usb/core/hub.c:5899 7 locks held by kworker/1:7/5822: #0: ffff888022e9a138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293 #1: ffffc900059efc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294 #2: ffff88802ab6e210 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline] #2: ffff88802ab6e210 (&dev->mutex){....}-{4:4}, at: hub_event+0x17c/0x4f60 drivers/usb/core/hub.c:5899 #3: ffff888065e0a210 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline] #3: ffff888065e0a210 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #4: ffffffff8f9566b8 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] #4: ffffffff8f9566b8 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x281/0x560 lib/kobject_uevent.c:410 #5: ffffffff8e2f5660 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] #5: ffffffff8e2f5660 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4534 [inline] #5: ffffffff8e2f5660 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4889 [inline] #5: ffffffff8e2f5660 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_noprof+0x44/0x680 mm/slub.c:4919 #6: ffffffff8e30ad20 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: fs_reclaim_acquire+0x7c/0x100 mm/page_alloc.c:4342 6 locks held by kworker/u8:24/7052: #0: ffff88813fe54138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x897/0x1630 kernel/workqueue.c:3293 #1: ffffc9000cb97c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work+0x8be/0x1630 kernel/workqueue.c:3294 #2: ffff888020ba6310 (&devlink->lock_key#11){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xbd0 drivers/net/netdevsim/dev.c:909 #3: ffff88805cc33120 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #3: ffff88805cc33120 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report drivers/net/netdevsim/dev.c:862 [inline] #3: ffff88805cc33120 (&nsim_trap_data->trap_lock){+.+.}-{3:3}, at: nsim_dev_trap_report_work+0x1ad/0xbd0 drivers/net/netdevsim/dev.c:922 #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #4: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline] #5: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa6/0x2550 arch/x86/kernel/unwind_orc.c:495 4 locks held by udevd/9658: #0: ffff88802875a3d8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb8/0xe20 fs/seq_file.c:183 #1: ffff88806da40478 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5c/0x420 fs/kernfs/file.c:172 #2: ffff888040b521e8 (kn->active#28){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #2: ffff888040b521e8 (kn->active#28){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:173 #3: ffff888065e0a210 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1107 [inline] #3: ffff888065e0a210 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142 2 locks held by syz.7.1586/10922: #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline] #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline] #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636 #1: ffff888027e78058 (&ep->mtx){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline] #1: ffff888027e78058 (&ep->mtx){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2573 [inline] #1: ffff888027e78058 (&ep->mtx){+.+.}-{4:4}, at: do_epoll_ctl_file+0xc69/0xed0 fs/eventpoll.c:2636 1 lock held by syz.0.1629/11021: #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: epoll_mutex_lock fs/eventpoll.c:2512 [inline] #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: ep_ctl_lock fs/eventpoll.c:2559 [inline] #0: ffffffff8e3589b8 (epnested_mutex){+.+.}-{4:4}, at: do_epoll_ctl_file+0x9d1/0xed0 fs/eventpoll.c:2636 4 locks held by syz.9.2190/13040: #0: ffff888037c01f30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:592 [inline] #0: ffff888037c01f30 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x194/0x9e0 mm/mmap.c:1284 #1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #1: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290 #2: ffff88804d57e298 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #2: ffff88804d57e298 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404 #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #3: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 3 locks held by syz.9.2190/13044: #0: ffff88802c1e8480 (sb_writers#5){.+.+}-{0:0}, at: do_coredump fs/coredump.c:1131 [inline] #0: ffff88802c1e8480 (sb_writers#5){.+.+}-{0:0}, at: vfs_coredump+0x3805/0x4570 fs/coredump.c:1200 #1: ffff88805dbb3f48 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff88805dbb3f48 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: shmem_file_write_iter+0x82/0x120 mm/shmem.c:3405 #2: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #2: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8e1cac60 (rcu_read_lock){....}-{1:3}, at: __update_page_owner_handle+0x5a/0x570 mm/page_owner.c:255 1 lock held by syz.8.2211/13104: #0: ffff888040521038 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #0: ffff888040521038 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x89/0x250 net/socket.c:725 1 lock held by syz.9.2213/13112: #0: ffffffff8f9566b8 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] #0: ffffffff8f9566b8 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x281/0x560 lib/kobject_uevent.c:410 1 lock held by syz.3.2216/13126: #0: ffffffff8e1d0e30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 39 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65 trigger_all_cpu_backtrace include/linux/nmi.h:162 [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:353 [inline] watchdog+0xfd3/0x1030 kernel/hung_task.c:561 kthread+0x388/0x470 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: 17 Comm: pr/legacy Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:io_serial_out+0x7c/0xc0 drivers/tty/serial/8250/8250_port.c:408 Code: 35 7a fc 44 89 f9 d3 e5 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 4c e0 e4 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d e9 57 c7 f2 05 cc 44 89 f9 80 e1 07 38 c1 RSP: 0018:ffffc90000167a50 EFLAGS: 00000206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000000003f9 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffffff854b6540 R12: dffffc0000000000 R13: ffffffff99e0ffc0 R14: ffffffff99e10040 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125c7e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c319965 CR3: 00000000312ba000 CR4: 00000000003526f0 Call Trace: serial_out drivers/tty/serial/8250/8250.h:133 [inline] serial8250_clear_IER drivers/tty/serial/8250/8250_port.c:-1 [inline] serial8250_console_write+0x3c1/0x1b50 drivers/tty/serial/8250/8250_port.c:3344 console_emit_next_record kernel/printk/printk.c:3163 [inline] console_flush_one_record+0x68b/0xb90 kernel/printk/printk.c:3269 legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712 kthread+0x388/0x470 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