rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=27e/1/0x4000000000000002 softirq=23607/23607 fqs=33 (t=10500 jiffies g=33589 q=724) rcu: rcu_preempt kthread starved for 10426 jiffies! g33589 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt I29440 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3265 [inline] __schedule+0x76e/0x17a0 kernel/sched/core.c:3937 schedule+0xd9/0x260 kernel/sched/core.c:4004 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1893 rcu_gp_fqs_loop kernel/rcu/tree.c:1639 [inline] rcu_gp_kthread+0x9b2/0x18d0 kernel/rcu/tree.c:1799 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 24318 Comm: syz-executor.2 Not tainted 5.3.0-rc6-next-20190830 #75 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+0x172/0x1f0 lib/dump_stack.c:113 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_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2795 [inline] rcu_sched_clock_irq.cold+0x4fd/0xc12 kernel/rcu/tree.c:2244 update_process_times+0x2d/0x70 kernel/time/timer.c:1724 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1299 __run_hrtimer kernel/time/hrtimer.c:1504 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1566 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1628 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1106 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1131 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 RIP: 0010:__sanitizer_cov_trace_pc+0x2b/0x50 kernel/kcov.c:105 Code: 48 89 e5 65 48 8b 04 25 40 fe 01 00 65 8b 15 e4 a7 8f 7e 81 e2 00 01 1f 00 48 8b 75 08 75 2b 8b 90 00 13 00 00 83 fa 02 75 20 <48> 8b 88 08 13 00 00 8b 80 04 13 00 00 48 8b 11 48 83 c2 01 48 39 RSP: 0018:ffff88805a8a6978 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffff888059f7c6c0 RBX: ffff88809fc9b2f8 RCX: ffffffff85cb6f79 RDX: 0000000000000002 RSI: ffffffff85cb6f8b RDI: 0000000000000001 RBP: ffff88805a8a6978 R08: ffff888059f7c6c0 R09: fffffbfff14ed341 R10: ffff888059f7d078 R11: ffff888059f7c6c0 R12: dffffc0000000000 R13: ffff88809fc9b000 R14: ffff88809fc9b398 R15: ffff88809fc9b390 __list_add include/linux/list.h:63 [inline] list_add_tail include/linux/list.h:93 [inline] list_move_tail include/linux/list.h:214 [inline] hhf_dequeue+0x68b/0xa20 net/sched/sch_hhf.c:439 dequeue_skb net/sched/sch_generic.c:258 [inline] qdisc_restart net/sched/sch_generic.c:361 [inline] __qdisc_run+0x1e7/0x19d0 net/sched/sch_generic.c:379 __dev_xmit_skb net/core/dev.c:3533 [inline] __dev_queue_xmit+0x16f1/0x37c0 net/core/dev.c:3838 dev_queue_xmit+0x18/0x20 net/core/dev.c:3902 br_dev_queue_push_xmit+0x3f3/0x5e0 net/bridge/br_forward.c:52 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] br_forward_finish+0xfa/0x400 net/bridge/br_forward.c:65 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] __br_forward+0x641/0xb00 net/bridge/br_forward.c:109 deliver_clone+0x61/0xc0 net/bridge/br_forward.c:125 maybe_deliver+0x2c7/0x390 net/bridge/br_forward.c:181 br_flood+0x13a/0x3d0 net/bridge/br_forward.c:223 br_dev_xmit+0x98c/0x15a0 net/bridge/br_device.c:100 __netdev_start_xmit include/linux/netdevice.h:4419 [inline] netdev_start_xmit include/linux/netdevice.h:4433 [inline] xmit_one net/core/dev.c:3280 [inline] dev_hard_start_xmit+0x1a3/0x9c0 net/core/dev.c:3296 __dev_queue_xmit+0x2b82/0x37c0 net/core/dev.c:3869 dev_queue_xmit+0x18/0x20 net/core/dev.c:3902 neigh_resolve_output net/core/neighbour.c:1490 [inline] neigh_resolve_output+0x5a5/0x970 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x1034/0x2550 net/ipv6/ip6_output.c:116 __ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip6_xmit+0xe35/0x20b0 net/ipv6/ip6_output.c:279 inet6_csk_xmit+0x2fb/0x5d0 net/ipv6/inet6_connection_sock.c:135 l2tp_xmit_core net/l2tp/l2tp_core.c:1030 [inline] l2tp_xmit_skb+0xfc1/0x1270 net/l2tp/l2tp_core.c:1132 pppol2tp_sendmsg+0x4af/0x6c0 net/l2tp/l2tp_ppp.c:325 sock_sendmsg_nosec net/socket.c:637 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:657 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2311 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2413 __do_sys_sendmmsg net/socket.c:2442 [inline] __se_sys_sendmmsg net/socket.c:2439 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2439 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598e9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f5ef0267c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004598e9 RDX: 0800000000000059 RSI: 0000000020005fc0 RDI: 0000000000000006 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5ef02686d4 R13: 00000000004c70a7 R14: 00000000004dc768 R15: 00000000ffffffff