INFO: task syz.6.854:7654 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.854 state:D stack:27408 pid: 7654 ppid: 5569 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093 __down_common+0x289/0x3b0 kernel/locking/semaphore.c:228 down+0x7e/0xd0 kernel/locking/semaphore.c:63 console_lock+0x29/0x70 kernel/printk/printk.c:2557 con_install+0x94/0x720 drivers/tty/vt/vt.c:3384 tty_driver_install_tty drivers/tty/tty_io.c:1306 [inline] tty_init_dev+0xbb/0x470 drivers/tty/tty_io.c:1418 tty_open_by_driver drivers/tty/tty_io.c:2085 [inline] tty_open+0x7e8/0xcd0 drivers/tty/tty_io.c:2132 chrdev_open+0x585/0x5f0 fs/char_dev.c:414 do_dentry_open+0x7f7/0xf90 fs/open.c:826 do_open fs/namei.c:3659 [inline] path_openat+0x2718/0x2fb0 fs/namei.c:3793 do_filp_open+0x1df/0x400 fs/namei.c:3820 do_sys_openat2+0x14b/0x500 fs/open.c:1255 do_sys_open fs/open.c:1271 [inline] __do_sys_openat fs/open.c:1287 [inline] __se_sys_openat fs/open.c:1282 [inline] __x64_sys_openat+0x135/0x160 fs/open.c:1282 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fdc4c10434e RSP: 002b:00007fdc4a399b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fdc4a39a6c0 RCX: 00007fdc4c10434e RDX: 0000000000000002 RSI: 00007fdc4a399c00 RDI: ffffffffffffff9c RBP: 00007fdc4c1dbb70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdc4c3ca038 R14: 00007fdc4c3c9fa0 R15: 00007fff3a858e58 Showing all locks held in the system: 1 lock held by khungtaskd/27: #0: ffffffff8d11efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 1 lock held by klogd/3549: 1 lock held by udevd/3560: 2 locks held by getty/3942: #0: ffff88802d48d098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158 6 locks held by kworker/u4:4/4244: #0: ffff888019ba2138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc9000318fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff88802b5fc0e0 (&type->s_umount_key#32){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418 #3: ffff88802b5fec58 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x213/0x2d40 fs/ext4/inode.c:2691 #4: ffff88814cff8990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 #5: ffff8880753a3e48 (&ei->i_data_sem){++++}-{3:3}, at: ext4_map_blocks+0x8c4/0x1a50 fs/ext4/inode.c:668 3 locks held by kworker/0:6/4281: #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc9000316fd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff888044a66240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x283/0x3380 drivers/net/netdevsim/fib.c:1480 3 locks held by kworker/0:8/4284: 3 locks held by kworker/u4:5/4293: 5 locks held by syz.0.573/6256: 7 locks held by kworker/0:10/7161: #0: ffff88801cacdd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc900035bfd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff888025170220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline] #2: ffff888025170220 (&dev->mutex){....}-{3:3}, at: hub_event+0x178/0x5260 drivers/usb/core/hub.c:5837 #3: ffff888041369220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline] #3: ffff888041369220 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:974 #4: ffff8880543f01a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline] #4: ffff8880543f01a8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:974 #5: ffff8880251735c8 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3178 [inline] #5: ffff8880251735c8 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_reset_device+0x51e/0xaa0 drivers/usb/core/hub.c:6340 #6: ffff8880245c3568 (hcd->address0_mutex){+.+.}-{3:3}, at: usb_reset_and_verify_device+0x42a/0x1730 drivers/usb/core/hub.c:6137 2 locks held by syz.6.854/7654: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2049 [inline] #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2132 #1: ffff88807b93e1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x6f/0x470 drivers/tty/tty_io.c:1417 1 lock held by syz.1.907/7895: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.5.883/8029: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823 3 locks held by kworker/0:18/8253: #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc900035efd00 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline] #2: ffffffff8d123a28 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845 3 locks held by syz.7.992/8420: #0: ffff888078b81c70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056 #1: ffff88806527de80 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x9d/0xc50 fs/seq_file.c:182 #2: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: t_start+0x17/0x50 fs/proc/proc_tty.c:108 1 lock held by syz.0.1018/8563: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.8.1073/8860: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2049 [inline] #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2132 1 lock held by syz.3.1124/9159: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.2.1139/9241: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.2.1139/9244: #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2049 [inline] #0: ffffffff8d7f6ee8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2132 1 lock held by syz-executor/9451: 4 locks held by udevd/9595: #0: ffff88806527d1c8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x9d/0xc50 fs/seq_file.c:182 #1: ffff88805f43f488 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x55/0x3c0 fs/kernfs/file.c:112 #2: ffff88807c773ae8 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x75/0x3c0 fs/kernfs/file.c:113 #3: ffff888041369220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline] #3: ffff888041369220 (&dev->mutex){....}-{3:3}, at: uevent_show+0x16c/0x320 drivers/base/core.c:2408 1 lock held by syz.6.1185/9599: 1 lock held by syz.1.1201/9677: #0: ffff88807c590128 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #0: ffff88807c590128 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x16c/0x2d0 mm/util.c:549 1 lock held by syz.1.1201/9678: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline] watchdog+0xe1b/0xe60 kernel/hung_task.c:369 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287