INFO: task :9376 can't die for more than 143 seconds. R running task 28144 9376 9017 0x00004006 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x8e1/0x1f30 kernel/sched/core.c:4081 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ffff8880ae837358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline] #0: ffff8880ae837358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f30 kernel/sched/core.c:4029 #1: ffff8880a9a17dc0 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 #2: ffff8880ae827258 (&base->lock){-.-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:936 1 lock held by khungtaskd/972: #0: ffffffff88faccc0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 2 locks held by getty/8966: #0: ffff8880a097e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8967: #0: ffff888093c3f090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f3b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8968: #0: ffff88808e8be090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f372e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8969: #0: ffff8880a3a39090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8970: #0: ffff8880a80dc090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8971: #0: ffff888099c23090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/8972: #0: ffff88809ad40090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f092e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 972 Comm: khungtaskd Not tainted 5.4.0-rc7-next-20191115 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:269 [inline] watchdog+0xc8f/0x1350 kernel/hung_task.c:353 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.4.0-rc7-next-20191115 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:hlock_class kernel/locking/lockdep.c:163 [inline] RIP: 0010:mark_lock+0xca/0x1220 kernel/locking/lockdep.c:3643 Code: 20 66 81 e3 ff 1f 0f b7 db be 08 00 00 00 48 89 d8 48 c1 f8 06 48 8d 3c c5 a0 59 7a 8a e8 8e 74 56 00 48 0f a3 1d a6 d5 20 09 <0f> 83 be 00 00 00 48 69 db b0 00 00 00 48 81 c3 c0 5d 7a 8a 48 8d RSP: 0018:ffff8880a9a17a40 EFLAGS: 00000047 RAX: 0000000000000001 RBX: 000000000000058b RCX: ffffffff815983f2 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8a7a5a50 RBP: ffff8880a9a17a90 R08: 1ffffffff14f4b4a R09: fffffbfff14f4b4b R10: fffffbfff14f4b4a R11: ffffffff8a7a5a57 R12: 0000000000000008 R13: ffff8880a9a0ae70 R14: 0000000000000000 R15: 000000000004058b FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000960b7000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mark_usage kernel/locking/lockdep.c:3592 [inline] __lock_acquire+0x538/0x4a00 kernel/locking/lockdep.c:3909 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:343 [inline] batadv_nc_purge_paths+0xd8/0x370 net/batman-adv/network-coding.c:441 batadv_nc_worker+0x297/0x760 net/batman-adv/network-coding.c:719 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352