EXT4-fs (loop5): mounted filesystem without journal. Opts: ,errors=continue INFO: task kworker/u4:1:22 blocked for more than 140 seconds. Not tainted 4.14.223-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:1 D26680 22 2 0x80000000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x272/0x430 kernel/sched/completion.c:123 flush_workqueue+0x3ce/0x1310 kernel/workqueue.c:2676 flush_scheduled_work include/linux/workqueue.h:578 [inline] tipc_exit_net+0x38/0x60 net/tipc/core.c:96 ops_exit_list+0xa5/0x150 net/core/net_namespace.c:142 cleanup_net+0x3b3/0x840 net/core/net_namespace.c:484 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 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: 3 locks held by kworker/u4:1/22: #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x110/0x840 net/core/net_namespace.c:450 1 lock held by khungtaskd/1512: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 3 locks held by kworker/0:2/4615: #0: ("events"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087 #1: ((&smc->tcp_listen_work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091 #2: (&smc->clcsock_release_lock){+.+.}, at: [] smc_clcsock_accept net/smc/af_smc.c:600 [inline] #2: (&smc->clcsock_release_lock){+.+.}, at: [] smc_tcp_listen_work+0x6ac/0xb80 net/smc/af_smc.c:935 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1512 Comm: khungtaskd Not tainted 4.14.223-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+0x1b2/0x281 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x180 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+0x5b9/0xb40 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4618 Comm: systemd-journal Not tainted 4.14.223-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a17046c0 task.stack: ffff8880a1708000 RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:774 [inline] RIP: 0010:prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline] RIP: 0010:syscall_return_slowpath arch/x86/entry/common.c:270 [inline] RIP: 0010:do_syscall_64+0x37a/0x640 arch/x86/entry/common.c:297 RSP: 0018:ffff8880a170fef8 EFLAGS: 00000097 RAX: ffff8880a17046c0 RBX: ffff8880a17046c0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a1704f0c RBP: ffff8880a170ff58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffff8880a17046c0 R12: ffffffff88f09290 R13: ffff8880a170ffd0 R14: 1ffffffff11e1250 R15: 0000000000000000 FS: 00007f01f5ad78c0(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f01f1697018 CR3: 00000000a17b6000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: Code: ee 03 48 b8 00 00 00 00 00 fc ff df 41 80 3c 06 00 0f 85 d0 01 00 00 48 83 3d a2 42 f0 07 00 0f 84 d8 00 00 00 e8 47 d1 54 00 9c <58> 0f 1f 44 00 00 f6 c4 02 0f 85 ca 00 00 00 e8 32 d1 54 00 e8