rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10354 ticks this GP) idle=986/1/0x4000000000000002 softirq=50676/50676 fqs=7 (t=10501 jiffies g=39329 q=670850) rcu: rcu_preempt kthread starved for 10487 jiffies! g39329 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29040 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3380 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4080 schedule+0xdc/0x2b0 kernel/sched/core.c:4154 schedule_timeout+0x36e/0x8c0 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline] rcu_gp_kthread+0xa02/0x1b00 kernel/rcu/tree.c:1837 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: 21087 Comm: syz-executor.1 Not tainted 5.6.0-rc2-next-20200224-syzkaller #0 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+0x197/0x210 lib/dump_stack.c:118 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:165 [inline] rcu_dump_cpu_stacks+0x1a2/0x1ef kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline] check_cpu_stall kernel/rcu/tree_stall.h:549 [inline] rcu_pending kernel/rcu/tree.c:3226 [inline] rcu_sched_clock_irq.cold+0x570/0xcc2 kernel/rcu/tree.c:2297 update_process_times+0x2d/0x70 kernel/time/timer.c:1727 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline] RIP: 0010:slab_alloc mm/slab.c:3313 [inline] RIP: 0010:kmem_cache_alloc+0x283/0x710 mm/slab.c:3484 Code: 7e 0f 85 dc fe ff ff e8 8c c9 4b ff e9 d2 fe ff ff e8 91 e2 c6 ff 48 83 3d c1 25 ff 07 00 0f 84 51 03 00 00 48 8b 7d d0 57 9d <0f> 1f 44 00 00 e9 68 fe ff ff 31 d2 be 35 02 00 00 48 c7 c7 7e 04 RSP: 0018:ffffc90001297030 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: 0000000000000a20 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff8880a6694ab0 RDI: 0000000000000282 RBP: ffffc90001297098 R08: ffff8880a66941c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a5267a80 R13: ffff8880a5267a80 R14: 0000000000000a20 R15: ffff888144122600 dst_alloc+0x10e/0x200 net/core/dst.c:93 rt_dst_alloc+0x83/0x440 net/ipv4/route.c:1628 __mkroute_output net/ipv4/route.c:2444 [inline] ip_route_output_key_hash_rcu+0x8c9/0x2d30 net/ipv4/route.c:2674 ip_route_output_key_hash+0x1ef/0x360 net/ipv4/route.c:2500 __ip_route_output_key include/net/route.h:126 [inline] ip_route_output_flow+0x28/0xc0 net/ipv4/route.c:2763 ip_route_output_key include/net/route.h:136 [inline] ip_tunnel_xmit+0x774/0x2d0c net/ipv4/ip_tunnel.c:753 __gre_xmit+0x5e9/0x9a0 net/ipv4/ip_gre.c:448 ipgre_xmit+0x4e2/0xa70 net/ipv4/ip_gre.c:632 __netdev_start_xmit include/linux/netdevice.h:4523 [inline] netdev_start_xmit include/linux/netdevice.h:4537 [inline] xmit_one net/core/dev.c:3475 [inline] dev_hard_start_xmit+0x1a3/0x9b0 net/core/dev.c:3491 __dev_queue_xmit+0x25b0/0x3070 net/core/dev.c:4050 dev_queue_xmit+0x18/0x20 net/core/dev.c:4083 __bpf_tx_skb net/core/filter.c:2061 [inline] __bpf_redirect_common net/core/filter.c:2100 [inline] __bpf_redirect+0x797/0xca0 net/core/filter.c:2107 ____bpf_clone_redirect net/core/filter.c:2140 [inline] bpf_clone_redirect+0x2ca/0x470 net/core/filter.c:2112 bpf_prog_bebbfe2050753572+0x354/0x1000 bpf_dispatcher_nopfunc include/linux/bpf.h:521 [inline] bpf_test_run+0x426/0xd60 net/bpf/test_run.c:48 bpf_prog_test_run_skb+0xaeb/0x1590 net/bpf/test_run.c:388 bpf_prog_test_run kernel/bpf/syscall.c:2572 [inline] __do_sys_bpf+0xc5c/0x4130 kernel/bpf/syscall.c:3414 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:3355 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c429 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f037aa63c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f037aa646d4 RCX: 000000000045c429 RDX: 000000000000002c RSI: 0000000020000080 RDI: 000000000000000a RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000059 R14: 00000000004c2b33 R15: 000000000076bf2c