NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task kworker/u4:0:5 blocked for more than 140 seconds. Not tainted 4.14.175-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:0 D25632 5 2 0x80000000 Workqueue: netns cleanup_net Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x946/0xe40 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x241/0x390 kernel/sched/completion.c:144 _rcu_barrier+0x285/0x400 kernel/rcu/tree.c:3611 ops_exit_list.isra.0+0x9d/0x140 net/core/net_namespace.c:142 cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484 process_one_work+0x813/0x1540 kernel/workqueue.c:2116 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Showing all locks held in the system: 4 locks held by kworker/u4:0/5: #0: ("%s""netns"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("%s""netns"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("%s""netns"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x727/0x1540 kernel/workqueue.c:2087 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x761/0x1540 kernel/workqueue.c:2091 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x123/0x820 net/core/net_namespace.c:450 #3: (rcu_preempt_state.barrier_mutex){+.+.}, at: [] _rcu_barrier+0x56/0x400 kernel/rcu/tree.c:3546 1 lock held by khungtaskd/1057: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544 1 lock held by syz-executor.4/30517: #0: (rcu_preempt_state.barrier_mutex){+.+.}, at: [] _rcu_barrier+0x56/0x400 kernel/rcu/tree.c:3546 1 lock held by syz-executor.2/30512: #0: (rcu_preempt_state.barrier_mutex){+.+.}, at: [] _rcu_barrier+0x56/0x400 kernel/rcu/tree.c:3546 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.175-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e2/0xb80 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 30058 Comm: syz-executor.0 Not tainted 4.14.175-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880472a63c0 task.stack: ffff8881eaf98000 RIP: 0010:trace_hardirqs_off_caller+0x72/0x2b0 kernel/locking/lockdep.c:2946 RSP: 0000:ffff8881eaf9fc38 EFLAGS: 00000807 RAX: dffffc0000000000 RBX: ffff8880472a63c0 RCX: 1ffffffff10279a4 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880472a6c3c RBP: ffffffff8183674a R08: 0000000000000001 R09: 0000000000000001 R10: ffff8880472a6c68 R11: ffff8880472a63c0 R12: ffff8880472a63c0 R13: ffffffff81393ec1 R14: dffffc0000000000 R15: ffff8880472a6ae8 FS: 00007fa5b5765700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000003e979918 CR3: 000000020eb46000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kmem_cache_free+0x14a/0x2b0 mm/slab.c:3759 __sigqueue_free kernel/signal.c:419 [inline] dequeue_synchronous_signal kernel/signal.c:727 [inline] get_signal+0xba1/0x1ca0 kernel/signal.c:2313 do_signal+0x7c/0x1690 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x159/0x220 arch/x86/entry/common.c:160 prepare_exit_to_usermode+0x1af/0x210 arch/x86/entry/common.c:199 retint_user+0x8/0x18 RIP: 0033:0x405b89 RSP: 002b:00007fa5b5764a70 EFLAGS: 00010202 RAX: 000000003e979908 RBX: 00007fa5b57656d4 RCX: 0000000000416687 RDX: e0dec0719e25721d RSI: 0000000000000000 RDI: 000000000000000a RBP: 000000000076c180 R08: 00007fa5b5764a70 R09: 000000000076c180 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000beb R14: 00000000004ce128 R15: 000000000076c18c Code: 84 5e 01 00 00 65 4c 8b 24 25 40 ee 01 00 49 8d bc 24 7c 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 <48> 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 b8 01 00 00