INFO: task kworker/u4:9:6410 blocked for more than 140 seconds. Not tainted 4.14.68+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:9 D26200 6410 2 0x80000000 Workqueue: netns cleanup_net Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1718 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:7865 ip6_tnl_exit_net+0x3cd/0x580 net/ipv6/ip6_tunnel.c:2256 ops_exit_list.isra.3+0xa8/0x150 net/core/net_namespace.c:142 cleanup_net+0x3e9/0x880 net/core/net_namespace.c:483 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-executor6:12123 blocked for more than 140 seconds. Not tainted 4.14.68+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D28808 12123 1850 0x00000004 Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1718 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 flush_work+0x3b8/0x6e0 kernel/workqueue.c:2885 lru_add_drain_all_cpuslocked+0x2ef/0x450 mm/swap.c:722 lru_add_drain_all+0xf/0x20 mm/swap.c:730 do_mlock+0x8c/0x5c0 mm/mlock.c:673 SYSC_mlock mm/mlock.c:713 [inline] SyS_mlock+0x1d/0x30 mm/mlock.c:711 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x457099 RSP: 002b:00007f79a3aaec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000095 RAX: ffffffffffffffda RBX: 00007f79a3aaf6d4 RCX: 0000000000457099 RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000000020ffe000 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d3120 R14: 00000000004c814b R15: 0000000000000000 INFO: task syz-executor6:12125 blocked for more than 140 seconds. Not tainted 4.14.68+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D28424 12125 12123 0x00000004 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 lru_add_drain_all_cpuslocked+0x7f/0x450 mm/swap.c:704 lru_add_drain_all+0xf/0x20 mm/swap.c:730 do_mlock+0x8c/0x5c0 mm/mlock.c:673 SYSC_mlock mm/mlock.c:713 [inline] SyS_mlock+0x1d/0x30 mm/mlock.c:711 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x457099 RSP: 002b:00007f79a3aaec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000095 RAX: ffffffffffffffda RBX: 00007f79a3aaf6d4 RCX: 0000000000457099 RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000000020ffe000 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d3120 R14: 00000000004c814b R15: 0000000000000000 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 2 locks held by getty/1756: #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 4 locks held by kworker/u4:9/6410: #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 #3: (rcu_preempt_state.barrier_mutex){+.+.}, at: [] _rcu_barrier+0x5b/0x3f0 kernel/rcu/tree.c:3529 2 locks held by syz-executor6/12123: #0: (cpu_hotplug_lock.rw_sem){++++}, at: [] get_online_cpus include/linux/cpu.h:138 [inline] #0: (cpu_hotplug_lock.rw_sem){++++}, at: [] lru_add_drain_all+0xa/0x20 mm/swap.c:729 #1: (lock#4){+.+.}, at: [] lru_add_drain_all_cpuslocked+0x7f/0x450 mm/swap.c:704 2 locks held by syz-executor6/12125: #0: (cpu_hotplug_lock.rw_sem){++++}, at: [] get_online_cpus include/linux/cpu.h:138 [inline] #0: (cpu_hotplug_lock.rw_sem){++++}, at: [] lru_add_drain_all+0xa/0x20 mm/swap.c:729 #1: (lock#4){+.+.}, at: [] lru_add_drain_all_cpuslocked+0x7f/0x450 mm/swap.c:704 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.68+ #4 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12106 Comm: syz-executor1 Not tainted 4.14.68+ #4 task: ffff880199682f00 task.stack: ffff880199538000 RIP: 0033:0x4023c4 RSP: 002b:00007f2790fd4690 EFLAGS: 00000282 RAX: 00000000b1457404 RBX: 0000000000000007 RCX: 0000000000457099 RDX: 0000000000000000 RSI: 00007f2790fd46c0 RDI: 0000000000000007 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d7008 R14: 00000000004ca112 R15: 0000000000000000 FS: 00007f2790fd5700(0000) GS:ffff8801d7600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd9b929010 CR3: 00000001cc24e002 CR4: 00000000001606b0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600