INFO: task syz.9.1275:12274 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.9.1275 state:D stack:27912 pid:12274 ppid:10271 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6701 schedule+0xbd/0x170 kernel/sched/core.c:6775 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747 ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823 chrdev_open+0x58c/0x600 fs/char_dev.c:414 do_dentry_open+0x880/0x14b0 fs/open.c:929 do_open fs/namei.c:3683 [inline] path_openat+0x284f/0x3270 fs/namei.c:3844 do_filp_open+0x1f2/0x430 fs/namei.c:3871 do_sys_openat2+0x134/0x1d0 fs/open.c:1422 do_sys_open fs/open.c:1437 [inline] __do_sys_openat fs/open.c:1453 [inline] __se_sys_openat fs/open.c:1448 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1448 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fc80759e1d9 RSP: 002b:00007fc80849f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fc807825fa0 RCX: 00007fc80759e1d9 RDX: 0000000000008d00 RSI: 0000200000000140 RDI: ffffffffffffff9c RBP: 00007fc807635888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc807826038 R14: 00007fc807825fa0 R15: 00007ffea450db98 Showing all locks held in the system: 1 lock held by khungtaskd/29: #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6669 5 locks held by kworker/u4:8/3445: #0: ffff88801ae5d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #0: ffff88801ae5d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #1: ffffc9000c867d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #1: ffffc9000c867d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #2: ffffffff8f1c5810 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x140/0xb00 net/core/net_namespace.c:610 #3: ffffffff8f1d2888 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xf2/0xa00 net/core/dev.c:11788 #4: ffffffff8df37ab8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline] #4: ffffffff8df37ab8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3da/0x880 kernel/rcu/tree_exp.h:1004 2 locks held by getty/5527: #0: ffff88802de3b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217 2 locks held by kworker/0:5/5848: #0: ffff888018872d38 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #0: ffff888018872d38 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #1: ffffc900047efd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #1: ffffc900047efd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 2 locks held by kworker/u4:23/8911: #0: ffff888018871938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #0: ffff888018871938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #1: ffffc900034efd00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #1: ffffc900034efd00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 4 locks held by kworker/u4:24/8912: 4 locks held by syz.0.1196/11863: 1 lock held by syz.9.1275/12274: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.8.1328/12507: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.3.1338/12561: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline] #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127 1 lock held by syz.3.1338/12564: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline] #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127 1 lock held by syz.5.1443/12971: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline] #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127 1 lock held by syz.2.1560/13446: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823 1 lock held by syz.4.1745/14315: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline] #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127 1 lock held by syz.6.1757/14374: #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline] #0: ffffffff8e6b80a8 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127 2 locks held by syz.9.1823/14849: 1 lock held by syz.7.1832/14882: #0: ffffffff8f1d2888 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x7a4/0x1140 net/core/dev_ioctl.c:769 2 locks held by syz.8.1834/14887: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xf59/0xfa0 kernel/hung_task.c:379 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293