INFO: task syz.0.5004:21791 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.5004 state:D stack:28776 pid:21791 tgid:21787 ppid:12786 task_flags:0x400040 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75 ___down_common kernel/locking/semaphore.c:293 [inline] __down_common+0x371/0x8b0 kernel/locking/semaphore.c:318 down+0x74/0xa0 kernel/locking/semaphore.c:100 console_lock+0x5b/0xa0 kernel/printk/printk.c:2896 class_console_lock_constructor include/linux/console.h:734 [inline] vcs_open+0x64/0xc0 drivers/tty/vt/vc_screen.c:746 chrdev_open+0x234/0x6a0 fs/char_dev.c:411 do_dentry_open+0x6ab/0x14d0 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2873/0x4280 fs/namei.c:4863 do_file_open+0x20e/0x430 fs/namei.c:4892 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f33e659e0d9 RSP: 002b:00007f33e74b5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f33e6825fa0 RCX: 00007f33e659e0d9 RDX: 0000000000000000 RSI: 0000200000001080 RDI: ffffffffffffff9c RBP: 00007f33e6635024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f33e6826038 R14: 00007f33e6825fa0 R15: 00007ffcc5512598 Showing all locks held in the system: 3 locks held by kworker/u8:0/12: 1 lock held by khungtaskd/31: #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 2 locks held by kworker/u8:7/1124: #0: ffff88801f372940 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc900054efd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 2 locks held by kworker/u8:11/3407: #0: ffff88801f372940 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc9000e2dfd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 2 locks held by getty/5368: #0: ffff88803757d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211 3 locks held by kworker/0:6/12172: #0: ffff88801bc0f140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc90004eb7d08 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffff88802a376250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1b8/0x6310 drivers/net/netdevsim/fib.c:1490 6 locks held by syz.7.4988/21746: 2 locks held by kworker/u8:19/22167: 4 locks held by syz.6.5132/22516: #0: ffff88803202beb0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259 #1: ffff888032eb4450 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739 #2: ffff888053a01480 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336 #3: ffff88801f2ed878 (kn->active#86){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] #3: ffff88801f2ed878 (kn->active#86){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:337 4 locks held by syz.2.5160/22681: #0: ffff88807d70b0b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259 #1: ffff88802c08c450 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739 #2: ffff888029bc9c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336 #3: ffff88801f2ed878 (kn->active#86){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] #3: ffff88801f2ed878 (kn->active#86){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:337 2 locks held by syz.3.5260/23451: #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120 #1: ffff8880342181b0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x39/0x470 drivers/tty/tty_io.c:1406 1 lock held by syz.5.5279/23559: #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120 1 lock held by syz.1.5283/23583: #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x360 drivers/tty/pty.c:767 1 lock held by syz.4.5286/23596: #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x360 drivers/tty/pty.c:767 1 lock held by syz.8.5287/23642: #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f986e60 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120 4 locks held by syz-executor/23712: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 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+0x141/0x190 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xcb1/0x1030 kernel/hung_task.c:561 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245