INFO: task syz.4.1686:13056 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.4.1686 state:D stack:26632 pid:13056 tgid:13055 ppid:13016 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x257/0x290 kernel/time/sleep_timeout.c:75 ___down_common kernel/locking/semaphore.c:268 [inline] __down_common+0x31f/0x6e0 kernel/locking/semaphore.c:293 down+0x74/0xa0 kernel/locking/semaphore.c:100 console_lock+0x5b/0xa0 kernel/printk/printk.c:2843 class_console_lock_constructor include/linux/console.h:737 [inline] con_install+0x99/0x600 drivers/tty/vt/vt.c:3647 tty_driver_install_tty drivers/tty/tty_io.c:1295 [inline] tty_init_dev.part.0+0x9c/0x500 drivers/tty/tty_io.c:1407 tty_init_dev include/linux/err.h:78 [inline] tty_open_by_driver drivers/tty/tty_io.c:2073 [inline] tty_open+0xa4f/0xf90 drivers/tty/tty_io.c:2120 chrdev_open+0x234/0x6a0 fs/char_dev.c:414 do_dentry_open+0x748/0x1590 fs/open.c:962 vfs_open+0x82/0x3f0 fs/open.c:1094 do_open fs/namei.c:4628 [inline] path_openat+0x2078/0x3140 fs/namei.c:4787 do_filp_open+0x20b/0x470 fs/namei.c:4814 do_sys_openat2+0x121/0x290 fs/open.c:1430 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1447 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f478a18f7c9 RSP: 002b:00007f478aff2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f478a3e5fa0 RCX: 00007f478a18f7c9 RDX: 0000000000000800 RSI: 0000200000000000 RDI: ffffffffffffff9c RBP: 00007f478a213f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f478a3e6038 R14: 00007f478a3e5fa0 R15: 00007ffca96fbe08 Showing all locks held in the system: 1 lock held by khungtaskd/31: #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775 3 locks held by kworker/1:4/5886: 2 locks held by getty/8261: #0: ffff88814d56b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc90003d952f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211 6 locks held by syz.1.1666/12960: 2 locks held by syz.4.1686/13056: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 #1: ffff8880558041c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x37/0x500 drivers/tty/tty_io.c:1406 1 lock held by syz.3.1717/13119: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.2.1720/13138: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.6.1744/13246: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.8.1739/13295: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.8.1739/13298: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.7.1764/13358: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.9.1771/13417: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.1.1777/13452: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.4.1791/13538: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.3.1795/13567: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.2.1801/13617: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 3 locks held by kworker/u8:29/13628: 1 lock held by syz.6.1816/13737: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.6.1816/13741: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.8.1824/13787: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.7.1845/13900: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.7.1845/13901: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.9.1846/13910: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765 1 lock held by syz.1.1844/13933: #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f071f88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz-executor/13967: #0: ffffffff90145528 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff90145528 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x30c/0x1540 net/ipv4/devinet.c:978 7 locks held by syz-executor/13994: #0: ffff8880317ea420 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:738 #1: ffff8880a9080088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x570 fs/kernfs/file.c:343 #2: ffff88814370f5a8 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #2: ffff88814370f5a8 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2ff/0x570 fs/kernfs/file.c:344 #3: ffffffff8f6bb148 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd1/0x4a0 drivers/net/netdevsim/bus.c:234 #4: ffff88803298d0e8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline] #4: ffff88803298d0e8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1104 [inline] #4: ffff88803298d0e8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa4/0x620 drivers/base/dd.c:1302 #5: ffff888032989250 (&devlink->lock_key#14){+.+.}-{4:4}, at: nsim_drv_remove+0x4a/0x1d0 drivers/net/netdevsim/dev.c:1777 #6: ffffffff8e3d4b40 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6e0 kernel/rcu/tree.c:3816 1 lock held by syz.0.1863/14005: 3 locks held by kworker/u8:43/14029: #0: ffff888030817148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232 #1: ffffc9000c1afc90 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233 #2: ffffffff90145528 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #2: ffffffff90145528 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x120/0x14f0 net/ipv6/addrconf.c:4194 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 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] __sys_info lib/sys_info.c:157 [inline] sys_info+0x133/0x180 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline] watchdog+0xe66/0x1180 kernel/hung_task.c:515 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246