INFO: task syz.4.2717:759 blocked for more than 149 seconds. Tainted: G U syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.4.2717 state:D stack:28872 pid:759 tgid:750 ppid:23969 task_flags:0x400040 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115 __mutex_lock_common kernel/locking/mutex.c:676 [inline] __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760 tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 chrdev_open+0x231/0x6a0 fs/char_dev.c:414 do_dentry_open+0x97f/0x1530 fs/open.c:965 vfs_open+0x82/0x3f0 fs/open.c:1095 do_open fs/namei.c:3887 [inline] path_openat+0x1de4/0x2cb0 fs/namei.c:4046 do_filp_open+0x20b/0x470 fs/namei.c:4073 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fac7a58ec29 RSP: 002b:00007fac7b415038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fac7a7d6090 RCX: 00007fac7a58ec29 RDX: 0000000000000001 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007fac7a611e41 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fac7a7d6128 R14: 00007fac7a7d6090 R15: 00007fff52c3f1b8 Showing all locks held in the system: 5 locks held by kworker/0:1/10: 1 lock held by khungtaskd/31: #0: ffffffff8e5c1420 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e5c1420 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e5c1420 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775 1 lock held by kcompactd0/34: 4 locks held by kworker/0:2/844: 1 lock held by syslogd/5219: #0: ffff888032375a88 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11b/0x530 mm/mmap_lock.c:147 1 lock held by klogd/5226: #0: ffff88802f92f1c8 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11b/0x530 mm/mmap_lock.c:147 4 locks held by udevd/5237: 1 lock held by dhcpcd/5531: #0: ffff888063204e48 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11b/0x530 mm/mmap_lock.c:147 1 lock held by crond/5610: 2 locks held by syz-executor/5854: 3 locks held by kworker/0:6/5970: 3 locks held by kworker/u10:2/22138: #0: ffff8880306ec948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211 #1: ffffc900050efd10 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212 #2: ffffffff90388b88 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #2: ffffffff90388b88 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4734 3 locks held by kworker/u10:9/24738: 3 locks held by kworker/u10:10/24739: 7 locks held by kworker/u10:11/24740: 4 locks held by kworker/u10:13/24742: 3 locks held by kworker/u10:18/24747: 4 locks held by kworker/u10:19/24748: 3 locks held by kworker/u10:20/24749: 3 locks held by kworker/u10:22/24751: 3 locks held by kworker/u10:23/24752: 3 locks held by kworker/u10:24/24753: 3 locks held by kworker/u10:26/24756: 3 locks held by kworker/u10:28/24834: 3 locks held by kworker/u10:29/24835: 3 locks held by kworker/u10:31/24837: 4 locks held by kworker/u10:32/24838: 2 locks held by getty/26303: #0: ffff888034e940a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc90002f042f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222 3 locks held by kworker/u10:33/27775: 4 locks held by kworker/u10:39/27781: 4 locks held by kworker/u10:40/27782: 3 locks held by syz-executor/27911: 4 locks held by kworker/0:0/28569: #0: ffff88801b882148 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211 #1: ffffc90005497d10 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212 #2: ffffffff90388b88 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0x83/0x1180 net/wireless/reg.c:2483 #3: ffff888032700768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6212 [inline] #3: ffff888032700768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_leave_invalid_chans net/wireless/reg.c:2471 [inline] #3: ffff888032700768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_check_chans_work+0x10d/0x1180 net/wireless/reg.c:2486 3 locks held by kworker/0:7/28660: #0: ffff88801b880d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211 #1: ffffc90004d3fd10 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212 #2: ffffffff90388b88 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104 3 locks held by syz-executor/28946: 3 locks held by syz.3.2711/726: 2 locks held by syz.2.2715/753: 1 lock held by syz.4.2717/759: #0: ffffffff8f2cc988 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2cc988 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U syzkaller #0 PREEMPT(full) Tainted: [U]=USER Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline] watchdog+0xf0e/0x1260 kernel/hung_task.c:491 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245