INFO: task syz.1.4175:19510 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.1.4175 state:D stack:26032 pid:19510 ppid:15861 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x107f/0x4030 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 perf_pending_task_sync kernel/events/core.c:5031 [inline] _free_event+0x176/0x1050 kernel/events/core.c:5037 put_event kernel/events/core.c:5162 [inline] perf_event_release_kernel+0x7c4/0x850 kernel/events/core.c:5287 perf_release+0x37/0x40 kernel/events/core.c:5297 __fput+0x20a/0x8b0 fs/file_table.c:320 task_work_run+0x1d0/0x260 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0x9d5/0x2570 kernel/exit.c:881 do_group_exit+0x229/0x2e0 kernel/exit.c:1024 get_signal+0x1259/0x1340 kernel/signal.c:2872 arch_do_signal_or_restart+0xc4/0x1310 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f0e8a19de59 RSP: 002b:00007f0e8b028028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: 0000000000000007 RBX: 00007f0e8a425fa0 RCX: 00007f0e8a19de59 RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000000 RBP: 00007f0e8a233e6f R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0e8a426038 R14: 00007f0e8a425fa0 R15: 00007ffeb0338888 Showing all locks held in the system: 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517 1 lock held by khungtaskd/28: #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527 2 locks held by getty/4027: #0: ffff888030134098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198 2 locks held by kworker/1:8/4347: #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc90004597d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 3 locks held by kworker/u4:13/10167: #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc900032c7d00 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #2: ffffffff8cb33700 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x48/0x5e0 kernel/rcu/tree.c:4023 4 locks held by kworker/u4:14/10168: 3 locks held by kworker/u4:15/11903: #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #1: ffffc9000e22fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267 #2: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263 2 locks held by syz.0.4842/22321: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: unregister_nexthop_notifier+0x7e/0x220 net/ipv4/nexthop.c:3635 2 locks held by syz.0.4842/22335: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: bareudp_exit_batch_net+0xb8/0x200 drivers/net/bareudp.c:787 2 locks held by syz.0.4842/22336: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8cb33700 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x48/0x5e0 kernel/rcu/tree.c:4023 2 locks held by syz.0.4842/22339: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: ppp_exit_net+0xee/0x350 drivers/net/ppp/ppp_generic.c:1159 1 lock held by syz.3.4840/22338: #0: ffffffff8cb8c828 (bpf_event_mutex){+.+.}-{3:3}, at: perf_event_detach_bpf_prog+0x87/0x310 kernel/trace/bpf_trace.c:2178 2 locks held by syz.5.4853/22384: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xd2/0x370 net/ipv4/ip_tunnel.c:1152 2 locks held by syz.3.4857/22399: #0: ffffffff8dd4bd90 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504 #1: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xd2/0x370 net/ipv4/ip_tunnel.c:1152 1 lock held by syz.2.4864/22422: #0: ffffffff8cb8c828 (bpf_event_mutex){+.+.}-{3:3}, at: perf_event_detach_bpf_prog+0x87/0x310 kernel/trace/bpf_trace.c:2178 2 locks held by syz.2.4864/22424: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline] #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3495 #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline] #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962 1 lock held by syz.4.4865/22427: #0: ffffffff8cb8c828 (bpf_event_mutex){+.+.}-{3:3}, at: perf_event_detach_bpf_prog+0x87/0x310 kernel/trace/bpf_trace.c:2178 1 lock held by syz.4.4865/22428: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3107 1 lock held by syz.4.4865/22429: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline] #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6155 1 lock held by syz.4.4865/22430: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3107 1 lock held by syz.4.4865/22431: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3107 1 lock held by syz.4.4865/22432: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3107 1 lock held by syz.4.4865/22433: #0: ffffffff8dd58c28 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3107 6 locks held by syz.4.4865/22434: #0: ffff88802850cae8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038 #1: ffff888145660460 (sb_writers#11){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580 #2: ffff888084983088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1d8/0x520 fs/kernfs/file.c:343 #3: ffffffff8cb56648 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:442 [inline] #3: ffffffff8cb56648 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xe5/0x220 kernel/cgroup/cgroup.c:1700 #4: ffffffff8c9ca530 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2476 [inline] #4: ffffffff8c9ca530 (cpu_hotplug_lock){++++}-{0:0}, at: cgroup_procs_write_start+0x186/0x610 kernel/cgroup/cgroup.c:2983 #5: ffffffff8cb56830 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_attach_lock kernel/cgroup/cgroup.c:2478 [inline] #5: ffffffff8cb56830 (cgroup_threadgroup_rwsem){++++}-{0:0}, at: cgroup_procs_write_start+0x19c/0x610 kernel/cgroup/cgroup.c:2983 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline] watchdog+0xf0e/0xf50 kernel/hung_task.c:377 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 20102 Comm: kworker/u4:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3723 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3743 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:3798 [inline] RIP: 0010:__lock_acquire+0x14e0/0x7c40 kernel/locking/lockdep.c:5063 Code: 68 90 4c 89 f8 48 c1 e8 03 48 89 44 24 30 42 80 3c 00 00 74 12 4c 89 ff e8 bd 39 6f 00 49 b8 00 00 00 00 00 fc ff df 49 8b 1f <48> 85 db 4c 89 b4 24 80 00 00 00 75 5d e8 be a4 ff ff 48 ba 00 00 RSP: 0018:ffffc900036875a0 EFLAGS: 00000046 RAX: 1ffffffff2109f84 RBX: ffffffff90b13ca8 RCX: ffffffff81640d65 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b10240 RBP: ffffc900036877d0 R08: dffffc0000000000 R09: 1ffffffff2162048 R10: dffffc0000000000 R11: fffffbfff2162049 R12: ffff88807cd3e4d8 R13: ffff88807cd3da00 R14: 47eb5074d03e3c30 R15: ffffffff9084fc20 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f87afdeb540 CR3: 000000000c88e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000008d24 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 __debug_object_init+0x5d/0x440 lib/debugobjects.c:670 init_timer_on_stack_key kernel/time/timer.c:805 [inline] schedule_timeout+0x12d/0x2d0 kernel/time/timer.c:2166 toggle_allocation_gate+0x25c/0x470 mm/kfence/core.c:828 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295