INFO: task kworker/u4:14:30602 blocked for more than 140 seconds. Not tainted 4.14.105+ #24 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:14 D26144 30602 2 0x80000000 Workqueue: netns cleanup_net Call Trace: schedule+0x92/0x1c0 kernel/sched/core.c:3492 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3550 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893 cleanup_net+0x136/0x860 net/core/net_namespace.c:449 process_one_work+0x7c6/0x14e0 kernel/workqueue.c:2114 worker_thread+0x5d7/0x1080 kernel/workqueue.c:2248 kthread+0x310/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 Showing all locks held in the system: 1 lock held by khungtaskd/23: #0: (tasklist_lock){.+.?}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4541 4 locks held by udevd/190: #0: (sb_writers#8){.+.+}, at: [] file_start_write include/linux/fs.h:2726 [inline] #0: (sb_writers#8){.+.+}, at: [] vfs_write+0x3d8/0x4d0 fs/read_write.c:545 #1: (&of->mutex){+.+.}, at: [] kernfs_fop_write+0x1d9/0x440 fs/kernfs/file.c:307 #2: (kn->count#4){++++}, at: [] kernfs_fop_write+0x1fc/0x440 fs/kernfs/file.c:308 #3: (uevent_sock_mutex){+.+.}, at: [] kobject_uevent_env+0x443/0xc60 lib/kobject_uevent.c:456 2 locks held by getty/1746: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1f7/0x1700 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:14/30602: #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x6e5/0x14e0 kernel/workqueue.c:2085 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x71b/0x14e0 kernel/workqueue.c:2089 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x136/0x860 net/core/net_namespace.c:449 1 lock held by syz-executor.2/30837: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.0/30852: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/30897: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/30937: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/30976: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31020: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.4/31025: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31059: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.0/31081: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31185: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31229: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31272: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31352: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31474: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31512: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31578: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.2/31718: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.1/32204: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.0/32273: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.4/32274: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.0/32324: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.0/32377: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 1 lock held by syz-executor.4/32391: #0: (net_mutex){+.+.}, at: [] copy_net_ns+0x156/0x440 net/core/net_namespace.c:409 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.105+ #24 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x10e lib/dump_stack.c:53 nmi_cpu_backtrace.cold+0x47/0x86 lib/nmi_backtrace.c:101 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 190 Comm: udevd Not tainted 4.14.105+ #24 task: ffff8881d4625e00 task.stack: ffff8881d47c0000 RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline] RIP: 0010:atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline] RIP: 0010:switch_mm_irqs_off+0x27c/0xdf0 arch/x86/mm/tlb.c:366 RSP: 0018:ffff8881d47c76b0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffffffff84348f20 RCX: 00000001d47b4000 RDX: ffff8881d46c9978 RSI: dffffc0000000000 RDI: 0000000000000000 RBP: ffff8881d46c9600 R08: 0000000000000001 R09: 0000000000000005 R10: ffff8881d46266f8 R11: 0000000000000001 R12: ffffffff84633364 R13: ffffffff8463336b R14: 0000000000000000 R15: ffff8881d4620005 FS: 00007f84bc1ae7a0(0000) GS:ffff8881db800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200092f8 CR3: 00000001d47b4006 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: switch_mm+0x33/0x70 arch/x86/mm/tlb.c:157 context_switch kernel/sched/core.c:2840 [inline] __schedule+0xd80/0x1f30 kernel/sched/core.c:3448 preempt_schedule_common+0x4f/0xd0 kernel/sched/core.c:3572 ___preempt_schedule+0x16/0x18 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0x65/0x70 kernel/locking/spinlock.c:192 __debug_check_no_obj_freed lib/debugobjects.c:760 [inline] debug_check_no_obj_freed+0x2a9/0x5c0 lib/debugobjects.c:776 slab_free_hook mm/slub.c:1382 [inline] slab_free_freelist_hook mm/slub.c:1410 [inline] slab_free mm/slub.c:2966 [inline] kmem_cache_free+0x1ab/0x330 mm/slub.c:2988 kfree_skbmem net/core/skbuff.c:586 [inline] kfree_skbmem+0xa0/0x100 net/core/skbuff.c:580 __kfree_skb net/core/skbuff.c:646 [inline] consume_skb+0xc6/0x340 net/core/skbuff.c:705 netlink_broadcast_filtered+0x2b3/0x9d0 net/netlink/af_netlink.c:1488 kobject_uevent_env+0x6ba/0xc60 lib/kobject_uevent.c:492 Code: 00 00 8b 04 24 48 8d 95 78 03 00 00 48 0f a3 02 72 0b 48 81 fd 20 8f 34 84 74 02 0f 0b f0 48 0f b3 02 f0 48 0f ab 83 78 03 00 00 <48> 8d bb 88 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48