INFO: task syz.6.1263:12174 blocked for more than 143 seconds. Tainted: G U L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.1263 state:D stack:26824 pid:12174 tgid:12168 ppid:8648 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x1138/0x5ee0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6964 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:4637 [inline] path_openat+0x2078/0x3140 fs/namei.c:4796 do_filp_open+0x20b/0x470 fs/namei.c:4823 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: 0033:0x7f6c9f78f7c9 RSP: 002b:00007f6ca05a5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f6c9f9e6090 RCX: 00007f6c9f78f7c9 RDX: 0000000000000800 RSI: 0000200000000000 RDI: ffffffffffffff9c RBP: 00007f6c9f813f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6c9f9e6128 R14: 00007f6c9f9e6090 R15: 00007ffdca707778 INFO: task syz.6.1263:12180 blocked for more than 143 seconds. Tainted: G U L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.1263 state:D stack:28808 pid:12180 tgid:12168 ppid:8648 task_flags:0x400140 flags:0x00080006 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x1138/0x5ee0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6964 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] vcs_open+0x64/0xc0 drivers/tty/vt/vc_screen.c:746 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:4637 [inline] path_openat+0x2078/0x3140 fs/namei.c:4796 do_filp_open+0x20b/0x470 fs/namei.c:4823 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: 0033:0x7f6c9f78f7c9 RSP: 002b:00007f6ca0584038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f6c9f9e6180 RCX: 00007f6c9f78f7c9 RDX: 000000000002a801 RSI: 0000200000000000 RDI: ffffffffffffff9c RBP: 00007f6c9f813f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6c9f9e6218 R14: 00007f6c9f9e6180 R15: 00007ffdca707778 INFO: task syz.7.1274:12225 blocked for more than 143 seconds. Tainted: G U L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.7.1274 state:D stack:27320 pid:12225 tgid:12224 ppid:11690 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x1138/0x5ee0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6964 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776 tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] tty_open+0x53d/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:4637 [inline] path_openat+0x2078/0x3140 fs/namei.c:4796 do_filp_open+0x20b/0x470 fs/namei.c:4823 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: 0033:0x7f0b5db8f7c9 RSP: 002b:00007f0b5eae2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f0b5dde5fa0 RCX: 00007f0b5db8f7c9 RDX: 0000000000000100 RSI: 00002000000046c0 RDI: ffffffffffffff9c RBP: 00007f0b5dc13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0b5dde6038 R14: 00007f0b5dde5fa0 R15: 00007ffe362bf6b8 Showing all locks held in the system: 1 lock held by kthreadd/2: 3 locks held by kworker/u8:0/12: 4 locks held by kworker/u8:1/13: 1 lock held by khungtaskd/31: #0: ffffffff8e3c94a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e3c94a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8e3c94a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775 4 locks held by kworker/u8:2/36: 1 lock held by khugepaged/38: #0: ffffffff8e506688 (lock#5){+.+.}-{4:4}, at: __lru_add_drain_all+0x6e/0x6f0 mm/swap.c:840 3 locks held by kworker/u8:3/49: 3 locks held by kworker/u8:4/79: 3 locks held by kworker/u8:5/285: 3 locks held by kworker/u8:6/1093: 3 locks held by kworker/u8:7/1159: 3 locks held by kworker/u8:8/1316: 2 locks held by kworker/R-bat_e/3408: 3 locks held by kworker/u8:9/3438: 4 locks held by kworker/u8:10/3494: 3 locks held by kworker/u8:11/3639: 3 locks held by kworker/u8:12/3689: 1 lock held by klogd/5189: 2 locks held by udevd/5200: 2 locks held by getty/5590: #0: ffff8880358360a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000331e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211 5 locks held by kworker/0:4/5898: 3 locks held by kworker/u8:13/6081: 2 locks held by kworker/u8:14/6096: #0: ffff88814269e148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232 #1: ffffc9000b567c90 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233 4 locks held by kworker/u8:15/6106: 3 locks held by kworker/u8:16/6329: 3 locks held by kworker/u8:17/6463: 3 locks held by kworker/u8:18/6483: 3 locks held by kworker/u8:20/7962: 4 locks held by kworker/u8:21/7963: 2 locks held by kworker/u8:22/7964: #0: ffff88814269e148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232 #1: ffffc9000c8cfc90 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233 1 lock held by syz.3.453/8472: 1 lock held by syz.3.453/8478: 3 locks held by kworker/u8:23/9985: 3 locks held by kworker/u8:24/9987: 2 locks held by kworker/u8:25/10307: 3 locks held by kworker/u8:26/10308: 3 locks held by kworker/u8:27/10309: 3 locks held by kworker/u8:28/10310: 3 locks held by kworker/u8:29/10311: 3 locks held by syz.5.1112/11469: #0: ffffffff901ec210 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e801508 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1596 #2: ffffffff902c52b0 ((inetaddr_chain).rwsem){++++}-{4:4}, at: __blocking_notifier_chain_register kernel/notifier.c:263 [inline] #2: ffffffff902c52b0 ((inetaddr_chain).rwsem){++++}-{4:4}, at: blocking_notifier_chain_register+0x69/0xd0 kernel/notifier.c:282 2 locks held by kworker/0:9/11792: 6 locks held by syz.0.1195/11886: 2 locks held by syz.6.1263/12174: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 #1: ffff8880788b21c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x37/0x500 drivers/tty/tty_io.c:1406 1 lock held by syz.7.1274/12225: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.9.1323/12646: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.9.1323/12650: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.1.1324/12664: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.1.1324/12666: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 2 locks held by syz-executor/12843: 1 lock held by syz.3.1328/13044: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 3 locks held by kworker/u8:30/13090: #0: ffff88803068e948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232 #1: ffffc90000bc7c90 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233 #2: ffffffff90145ae8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #2: ffffffff90145ae8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4734 2 locks held by syz.0.1354/13094: 1 lock held by syz.0.1372/13173: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.5.1379/13198: #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f072268 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf90 drivers/tty/tty_io.c:2120 3 locks held by kworker/u8:31/13207: 3 locks held by kworker/u8:32/13211: 3 locks held by syz-executor/13242: 2 locks held by dhcpcd-run-hook/13299: 2 locks held by udevd/13308: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP 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:161 [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