[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 55.269376][ T26] audit: type=1800 audit(1579939505.638:25): pid=8426 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 55.288535][ T26] audit: type=1800 audit(1579939505.648:26): pid=8426 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 55.309398][ T26] audit: type=1800 audit(1579939505.648:27): pid=8426 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.10.62' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 264.761254][ T8579] Set syz2 is full, maxelem 65536 reached [ 369.792046][ C0] rcu: INFO: rcu_preempt self-detected stall on CPU [ 369.798775][ C0] rcu: 0-...!: (1 GPs behind) idle=9ae/1/0x4000000000000002 softirq=14771/14772 fqs=15 [ 369.808694][ C0] (t=10502 jiffies g=5937 q=18) [ 369.813610][ C0] rcu: rcu_preempt kthread starved for 10473 jiffies! g5937 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 [ 369.824860][ C0] rcu: RCU grace-period kthread stack dump: [ 369.830724][ C0] rcu_preempt I29016 10 2 0x80004000 [ 369.837040][ C0] Call Trace: [ 369.840436][ C0] __schedule+0x87f/0xcd0 [ 369.844760][ C0] schedule+0x188/0x210 [ 369.848894][ C0] schedule_timeout+0x14f/0x240 [ 369.853796][ C0] ? run_local_timers+0x120/0x120 [ 369.858828][ C0] rcu_gp_kthread+0xe0d/0x1770 [ 369.863638][ C0] kthread+0x332/0x350 [ 369.867684][ C0] ? rcu_report_qs_rsp+0x140/0x140 [ 369.872771][ C0] ? kthread_blkcg+0xe0/0xe0 [ 369.877352][ C0] ret_from_fork+0x24/0x30 [ 369.881775][ C0] NMI backtrace for cpu 0 [ 369.886122][ C0] CPU: 0 PID: 8580 Comm: syz-executor207 Not tainted 5.5.0-rc7-syzkaller #0 [ 369.895724][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 369.905754][ C0] Call Trace: [ 369.909013][ C0] [ 369.911932][ C0] dump_stack+0x1fb/0x318 [ 369.916264][ C0] nmi_cpu_backtrace+0xaa/0x190 [ 369.921102][ C0] ? nmi_trigger_cpumask_backtrace+0x168/0x290 [ 369.927262][ C0] ? arch_trigger_cpumask_backtrace+0x20/0x20 [ 369.933303][ C0] nmi_trigger_cpumask_backtrace+0x16f/0x290 [ 369.939259][ C0] arch_trigger_cpumask_backtrace+0x10/0x20 [ 369.945129][ C0] rcu_dump_cpu_stacks+0x15a/0x220 [ 369.950390][ C0] rcu_sched_clock_irq+0x1521/0x1ab0 [ 369.955711][ C0] ? trace_hardirqs_off+0x74/0x80 [ 369.960716][ C0] update_process_times+0x12d/0x180 [ 369.965927][ C0] tick_sched_timer+0x263/0x420 [ 369.970764][ C0] ? tick_setup_sched_timer+0x3e0/0x3e0 [ 369.977330][ C0] __hrtimer_run_queues+0x3f3/0x840 [ 369.982510][ C0] hrtimer_interrupt+0x37c/0xda0 [ 369.987874][ C0] ? debug_smp_processor_id+0x9/0x20 [ 369.993502][ C0] smp_apic_timer_interrupt+0x109/0x280 [ 369.999137][ C0] apic_timer_interrupt+0xf/0x20 [ 370.004053][ C0] [ 370.007057][ C0] RIP: 0010:hash_ip4_expire+0x1f1/0x870 [ 370.012589][ C0] Code: 48 85 c0 0f 84 80 04 00 00 48 89 9d 68 ff ff ff 48 89 45 c8 48 8d 50 19 48 89 d0 48 c1 e8 03 48 89 85 70 ff ff ff 42 8a 04 30 <84> c0 48 89 55 d0 0f 85 a0 05 00 00 0f b6 1a 31 ff 89 de e8 27 38 [ 370.032178][ C0] RSP: 0018:ffffc90001db7038 EFLAGS: 00000a02 ORIG_RAX: ffffffffffffff13 [ 370.040579][ C0] RAX: 1ffff11012feba00 RBX: 1ffff11011363faf RCX: ffff88808e34c540 [ 370.048543][ C0] RDX: ffff888097f5d719 RSI: 0000000000000000 RDI: 0000000000000003 [ 370.056499][ C0] RBP: ffffc90001db7118 R08: ffffffff86a74cc1 R09: ffffed1012febb03 [ 370.064506][ C0] R10: ffffed1012febb03 R11: 0000000000000000 R12: ffff888089b1fd78 [ 370.072465][ C0] R13: ffff888089b00008 R14: dffffc0000000000 R15: ffff888089b00000 [ 370.080473][ C0] ? hash_ip4_expire+0x471/0x870 [ 370.085451][ C0] ? hash_ip4_expire+0x1a5/0x870 [ 370.090394][ C0] hash_ip4_add+0x147/0x1500 [ 370.094997][ C0] hash_ip4_uadt+0x589/0x810 [ 370.099573][ C0] ? hash_ip4_uadt+0x810/0x810 [ 370.105277][ C0] call_ad+0x10a/0x5b0 [ 370.109458][ C0] ? __nla_parse+0x41/0x50 [ 370.113863][ C0] ip_set_ad+0x6a9/0x860 [ 370.118112][ C0] ip_set_uadd+0x37/0x50 [ 370.122342][ C0] ? ip_set_dump+0x160/0x160 [ 370.126969][ C0] nfnetlink_rcv_msg+0x9ae/0xcd0 [ 370.131965][ C0] ? cap_capable+0x25b/0x290 [ 370.136531][ C0] ? cap_capable+0x25b/0x290 [ 370.141149][ C0] netlink_rcv_skb+0x19e/0x3e0 [ 370.145902][ C0] ? nfnetlink_bind+0x250/0x250 [ 370.150749][ C0] nfnetlink_rcv+0x1e0/0x1e50 [ 370.155426][ C0] ? rcu_lock_release+0x9/0x30 [ 370.160176][ C0] ? rcu_lock_release+0x21/0x30 [ 370.165026][ C0] ? netlink_deliver_tap+0x142/0x880 [ 370.170298][ C0] netlink_unicast+0x767/0x920 [ 370.175049][ C0] netlink_sendmsg+0xa2c/0xd50 [ 370.179804][ C0] ? netlink_getsockopt+0x9f0/0x9f0 [ 370.185055][ C0] ____sys_sendmsg+0x4f7/0x7f0 [ 370.189813][ C0] __sys_sendmsg+0x1ed/0x290 [ 370.194402][ C0] ? check_preemption_disabled+0xb4/0x260 [ 370.201049][ C0] ? debug_smp_processor_id+0x9/0x20 [ 370.206357][ C0] ? debug_smp_processor_id+0x1c/0x20 [ 370.211731][ C0] ? fpregs_assert_state_consistent+0xb6/0xe0 [ 370.217822][ C0] ? prepare_exit_to_usermode+0x221/0x5b0 [ 370.223652][ C0] ? trace_irq_disable_rcuidle+0x23/0x1e0 [ 370.229351][ C0] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 370.234784][ C0] ? trace_irq_disable_rcuidle+0x23/0x1e0 [ 370.240477][ C0] ? do_syscall_64+0x1d/0x1c0 [ 370.245134][ C0] __x64_sys_sendmsg+0x7f/0x90 [ 370.249877][ C0] do_syscall_64+0xf7/0x1c0 [ 370.255355][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 370.261218][ C0] RIP: 0033:0x441579 [ 370.265120][ C0] Code: e8 fc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 370.284698][ C0] RSP: 002b:00007fff97ce2e68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 370.293089][ C0] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441579 [ 370.301043][ C0] RDX: 0000000000000000 RSI: 0000000020000d00 RDI: 0000000000000004 [ 370.309112][ C0] RBP: 0000000000040767 R08: 00000000004002c8 R09: 00000000004002c8 [ 370.317062][ C0] R10: 00000000004002c8 R11: 0000000000000246 R12: 00000000004023a0 [ 370.325006][ C0] R13: 0000000000402430 R14: 0000000000000000 R15: 0000000000000000