INFO: task kworker/u4:2:379 blocked for more than 140 seconds. Not tainted 4.14.78+ #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:2 D25424 379 2 0x80000000 Workqueue: netns cleanup_net Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3548 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x521/0x1480 kernel/locking/mutex.c:893 cleanup_net+0x14c/0x880 net/core/net_namespace.c:449 process_one_work+0x86e/0x15c0 kernel/workqueue.c:2114 worker_thread+0xdc/0x1000 kernel/workqueue.c:2248 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 INFO: task syz-executor0:7462 blocked for more than 140 seconds. Not tainted 4.14.78+ #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D26728 7462 1860 0x80000006 Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1721 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x3bc/0x4e0 kernel/sched/completion.c:123 _rcu_barrier+0x27b/0x3f0 kernel/rcu/tree.c:3594 netdev_run_todo+0x112/0x750 net/core/dev.c:7889 tun_detach drivers/net/tun.c:587 [inline] tun_chr_close+0x45/0x50 drivers/net/tun.c:2655 __fput+0x25e/0x6f0 fs/file_table.c:210 task_work_run+0x116/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x8f8/0x2800 kernel/exit.c:865 do_group_exit+0x100/0x2e0 kernel/exit.c:968 get_signal+0x4e5/0x1470 kernel/signal.c:2348 do_signal+0x8f/0x1660 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x116/0x150 arch/x86/entry/common.c:159 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:267 [inline] do_syscall_64+0x35d/0x4b0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x411021 RSP: 002b:00007ffe76d07c70 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000411021 RDX: 0000000000000000 RSI: 00000000007308f0 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 00007ffe76d07b90 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000001 R14: 000000000000005e R15: 0000000000000000 INFO: task syz-executor5:7496 blocked for more than 140 seconds. Not tainted 4.14.78+ #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D27232 7496 1861 0x00000004 Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1721 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x3bc/0x4e0 kernel/sched/completion.c:123 __wait_rcu_gp+0x250/0x3a0 kernel/rcu/update.c:413 synchronize_rcu.part.43+0xd2/0xe0 kernel/rcu/tree_plugin.h:764 synchronize_net+0x3a/0x40 net/core/dev.c:8212 nf_register_net_hook+0x5e4/0x8c0 net/netfilter/core.c:294 nf_register_net_hooks+0x47/0xa0 net/netfilter/core.c:382 ops_init+0xad/0x3e0 net/core/net_namespace.c:118 setup_net+0x22b/0x510 net/core/net_namespace.c:294 copy_net_ns+0x193/0x430 net/core/net_namespace.c:418 create_new_namespaces+0x4f0/0x750 kernel/nsproxy.c:107 copy_namespaces+0x289/0x320 kernel/nsproxy.c:165 copy_process.part.6+0x1fb6/0x6530 kernel/fork.c:1765 copy_process kernel/fork.c:1573 [inline] _do_fork+0x1c2/0xd50 kernel/fork.c:2054 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x457569 RSP: 002b:00007f79415e4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569 RDX: 00000000200009c0 RSI: 0000000020000a00 RDI: 0000000070024100 RBP: 000000000072bf00 R08: 0000000020000980 R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 00007f79415e56d4 R13: 00000000004bd9e6 R14: 00000000004cc6c8 R15: 00000000ffffffff INFO: task syz-executor5:7522 blocked for more than 140 seconds. Not tainted 4.14.78+ #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D29272 7522 1861 0x00000004 Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1721 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x3bc/0x4e0 kernel/sched/completion.c:123 __wait_rcu_gp+0x250/0x3a0 kernel/rcu/update.c:413 synchronize_rcu.part.43+0xd2/0xe0 kernel/rcu/tree_plugin.h:764 namespace_unlock+0xef/0x110 fs/namespace.c:1466 put_mnt_ns+0x41/0x60 fs/namespace.c:3334 create_new_namespaces+0x35a/0x750 kernel/nsproxy.c:128 copy_namespaces+0x289/0x320 kernel/nsproxy.c:165 copy_process.part.6+0x1fb6/0x6530 kernel/fork.c:1765 copy_process kernel/fork.c:1573 [inline] _do_fork+0x1c2/0xd50 kernel/fork.c:2054 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x457569 RSP: 002b:00007f7941580c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569 RDX: 00000000200009c0 RSI: 0000000020000a00 RDI: 0000000070024100 RBP: 000000000072c0e0 R08: 0000000020000980 R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 00007f79415816d4 R13: 00000000004bd9e6 R14: 00000000004cc6c8 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/23: #0: (tasklist_lock){.+.?}, at: [] debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541 3 locks held by kworker/u4:2/379: #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x787/0x15c0 kernel/workqueue.c:2085 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x7bf/0x15c0 kernel/workqueue.c:2089 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x14c/0x880 net/core/net_namespace.c:449 2 locks held by getty/1774: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 1 lock held by syz-executor0/7462: #0: (rcu_preempt_state.barrier_mutex){+.+.}, at: [] _rcu_barrier+0x5b/0x3f0 kernel/rcu/tree.c:3529 1 lock held by syz-executor5/7496: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x14f/0x430 net/core/net_namespace.c:409 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 23 Comm: khungtaskd Not tainted 4.14.78+ #28 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x11b lib/dump_stack.c:53 nmi_cpu_backtrace.cold.0+0x47/0x85 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x574/0xa70 kernel/hung_task.c:252 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7443 Comm: syz-executor1 Not tainted 4.14.78+ #28 task: ffff88019c1c0000 task.stack: ffff88019b790000 RIP: 0033:0x4015b7 RSP: 002b:00007f96e3017690 EFLAGS: 00000282 RAX: 00000000f0c39189 RBX: 000000000000000b RCX: 0000000000457569 RDX: 0000000000000000 RSI: 00007f96e30176c0 RDI: 000000000000000b RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f96e3018700(0000) GS:ffff8801dbb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9aa98f0140 CR3: 00000001d059e002 CR4: 00000000001606a0