[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 56.807874][ T23] audit: type=1800 audit(1579844513.398:25): pid=8568 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 56.845491][ T23] audit: type=1800 audit(1579844513.398:26): pid=8568 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 56.874985][ T23] audit: type=1800 audit(1579844513.398:27): pid=8568 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 '10.128.0.98' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 249.461418][ T8720] Set syz2 is full, maxelem 65536 reached [ 354.465149][ C0] rcu: INFO: rcu_preempt self-detected stall on CPU [ 354.472075][ C0] rcu: 0-...!: (10508 ticks this GP) idle=83e/1/0x4000000000000002 softirq=12910/12912 fqs=15 [ 354.482559][ C0] (t=10500 jiffies g=6341 q=598) [ 354.487659][ C0] rcu: rcu_preempt kthread starved for 10470 jiffies! g6341 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 [ 354.498911][ C0] rcu: RCU grace-period kthread stack dump: [ 354.504777][ C0] rcu_preempt I29112 10 2 0x80004000 [ 354.511110][ C0] Call Trace: [ 354.514487][ C0] __schedule+0x87f/0xcd0 [ 354.518803][ C0] schedule+0x188/0x210 [ 354.522935][ C0] schedule_timeout+0x14f/0x240 [ 354.527800][ C0] ? run_local_timers+0x120/0x120 [ 354.532851][ C0] rcu_gp_kthread+0xe0d/0x1770 [ 354.537644][ C0] kthread+0x332/0x350 [ 354.541686][ C0] ? rcu_report_qs_rsp+0x140/0x140 [ 354.546775][ C0] ? kthread_blkcg+0xe0/0xe0 [ 354.551372][ C0] ret_from_fork+0x24/0x30 [ 354.555828][ C0] NMI backtrace for cpu 0 [ 354.560136][ C0] CPU: 0 PID: 8721 Comm: syz-executor551 Not tainted 5.5.0-rc7-syzkaller #0 [ 354.568776][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 354.578807][ C0] Call Trace: [ 354.582120][ C0] [ 354.585039][ C0] dump_stack+0x1fb/0x318 [ 354.589349][ C0] nmi_cpu_backtrace+0xaa/0x190 [ 354.594173][ C0] ? nmi_trigger_cpumask_backtrace+0x168/0x290 [ 354.600515][ C0] ? arch_trigger_cpumask_backtrace+0x20/0x20 [ 354.606563][ C0] nmi_trigger_cpumask_backtrace+0x16f/0x290 [ 354.612520][ C0] arch_trigger_cpumask_backtrace+0x10/0x20 [ 354.618386][ C0] rcu_dump_cpu_stacks+0x15a/0x220 [ 354.623514][ C0] rcu_sched_clock_irq+0x1521/0x1ab0 [ 354.628850][ C0] ? trace_hardirqs_off+0x74/0x80 [ 354.633850][ C0] update_process_times+0x12d/0x180 [ 354.639187][ C0] tick_sched_timer+0x263/0x420 [ 354.644126][ C0] ? tick_setup_sched_timer+0x3e0/0x3e0 [ 354.650180][ C0] __hrtimer_run_queues+0x3f3/0x840 [ 354.655366][ C0] hrtimer_interrupt+0x37c/0xda0 [ 354.660381][ C0] ? debug_smp_processor_id+0x9/0x20 [ 354.665655][ C0] smp_apic_timer_interrupt+0x109/0x280 [ 354.671198][ C0] apic_timer_interrupt+0xf/0x20 [ 354.676110][ C0] [ 354.679026][ C0] RIP: 0010:debug_lockdep_rcu_enabled+0x5d/0xe0 [ 354.685237][ C0] Code: c0 b0 c2 44 89 48 c1 e8 03 42 8a 04 38 84 c0 75 59 83 3d f5 b8 e1 07 00 74 28 65 4c 8b 34 25 c0 1d 02 00 49 81 c6 94 08 00 00 <4c> 89 f0 48 c1 e8 03 42 8a 04 38 84 c0 75 59 31 db 41 83 3e 00 0f [ 354.704823][ C0] RSP: 0018:ffffc90001ff7010 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 354.713211][ C0] RAX: 1ffffffff1289800 RBX: 0000000000000000 RCX: ffff88808f5b2200 [ 354.721157][ C0] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 [ 354.729114][ C0] RBP: ffffc90001ff7028 R08: ffffffff86a74cc1 R09: ffffed1013f569f3 [ 354.737075][ C0] R10: ffffed1013f569f3 R11: 0000000000000000 R12: ffff88809fab4f90 [ 354.745029][ C0] R13: ffff88808a700008 R14: ffff88808f5b2a94 R15: dffffc0000000000 [ 354.753080][ C0] ? hash_ip4_expire+0x471/0x870 [ 354.757999][ C0] hash_ip4_expire+0x1a5/0x870 [ 354.762747][ C0] hash_ip4_add+0x147/0x1500 [ 354.767317][ C0] hash_ip4_uadt+0x589/0x810 [ 354.771982][ C0] ? hash_ip4_uadt+0x810/0x810 [ 354.776750][ C0] call_ad+0x10a/0x5b0 [ 354.780897][ C0] ? __nla_parse+0x41/0x50 [ 354.785418][ C0] ip_set_ad+0x6a9/0x860 [ 354.789666][ C0] ip_set_uadd+0x37/0x50 [ 354.793895][ C0] ? ip_set_dump+0x160/0x160 [ 354.798517][ C0] nfnetlink_rcv_msg+0x9ae/0xcd0 [ 354.803509][ C0] ? cap_capable+0x25b/0x290 [ 354.808078][ C0] ? cap_capable+0x25b/0x290 [ 354.812693][ C0] netlink_rcv_skb+0x19e/0x3e0 [ 354.817441][ C0] ? nfnetlink_bind+0x250/0x250 [ 354.822278][ C0] nfnetlink_rcv+0x1e0/0x1e50 [ 354.826961][ C0] ? rcu_lock_release+0x9/0x30 [ 354.831713][ C0] ? rcu_lock_release+0x21/0x30 [ 354.836541][ C0] ? netlink_deliver_tap+0x142/0x880 [ 354.841808][ C0] netlink_unicast+0x767/0x920 [ 354.846596][ C0] netlink_sendmsg+0xa2c/0xd50 [ 354.851360][ C0] ? netlink_getsockopt+0x9f0/0x9f0 [ 354.856627][ C0] ____sys_sendmsg+0x4f7/0x7f0 [ 354.861461][ C0] __sys_sendmsg+0x1ed/0x290 [ 354.866049][ C0] ? check_preemption_disabled+0xb4/0x260 [ 354.871752][ C0] ? debug_smp_processor_id+0x9/0x20 [ 354.877017][ C0] ? debug_smp_processor_id+0x1c/0x20 [ 354.882393][ C0] ? fpregs_assert_state_consistent+0xb6/0xe0 [ 354.888587][ C0] ? prepare_exit_to_usermode+0x221/0x5b0 [ 354.894292][ C0] ? trace_irq_disable_rcuidle+0x23/0x1e0 [ 354.900106][ C0] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 354.905547][ C0] ? trace_irq_disable_rcuidle+0x23/0x1e0 [ 354.911245][ C0] ? do_syscall_64+0x1d/0x1c0 [ 354.915901][ C0] __x64_sys_sendmsg+0x7f/0x90 [ 354.920652][ C0] do_syscall_64+0xf7/0x1c0 [ 354.925155][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 354.931095][ C0] RIP: 0033:0x441579 [ 354.934986][ 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 [ 354.954894][ C0] RSP: 002b:00007ffec72f4fb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 354.963294][ C0] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441579 [ 354.971249][ C0] RDX: 0000000000000000 RSI: 0000000020000d00 RDI: 0000000000000004 [ 354.979209][ C0] RBP: 000000000003cb83 R08: 00000000004002c8 R09: 00000000004002c8 [ 354.987172][ C0] R10: 00000000004002c8 R11: 0000000000000246 R12: 00000000004023a0 [ 354.995132][ C0] R13: 0000000000402430 R14: 0000000000000000 R15: 0000000000000000