rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=e46/1/0x4000000000000002 softirq=11451/11451 fqs=23 (t=10501 jiffies g=6205 q=392) rcu: rcu_preempt kthread starved for 10452 jiffies! g6205 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 8174 Comm: syz-executor.1 Not tainted 5.4.0-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 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:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__sanitizer_cov_trace_pc+0x31/0x50 kernel/kcov.c:107 Code: 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83 fa 02 75 21 48 8b 91 88 13 00 00 48 8b 32 <48> 8d 7e 01 8b 89 84 13 00 00 48 39 cf 73 08 48 89 44 f2 08 48 89 RSP: 0018:ffffc90002397598 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81487433 RBX: 0000000000000000 RCX: ffff8880a68ba040 RDX: ffffc90005029000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: ffffc900023975c0 R08: 000000000003a768 R09: ffffed10125bc69f R10: ffffed10125bc69f R11: 0000000000000000 R12: dffffc0000000000 R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff888092de34e8 free_thread_stack+0x168/0x590 kernel/fork.c:280 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_common kernel/sched/core.c:4236 [inline] preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 vprintk_emit+0x36d/0x3a0 kernel/printk/printk.c:1997 vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0x62/0x8d kernel/printk/printk.c:2056 ovs_ct_limit_del_zone_limit net/openvswitch/conntrack.c:1989 [inline] ovs_ct_limit_cmd_del+0x4ec/0x7e0 net/openvswitch/conntrack.c:2163 genl_family_rcv_msg_doit net/netlink/genetlink.c:672 [inline] genl_family_rcv_msg net/netlink/genetlink.c:717 [inline] genl_rcv_msg+0xf17/0x13e0 net/netlink/genetlink.c:734 netlink_rcv_skb+0x19e/0x3d0 net/netlink/af_netlink.c:2477 genl_rcv+0x28/0x40 net/netlink/genetlink.c:745 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0x767/0x920 net/netlink/af_netlink.c:1328 netlink_sendmsg+0xa21/0xd40 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:639 [inline] sock_sendmsg net/socket.c:659 [inline] ____sys_sendmsg+0x509/0x820 net/socket.c:2330 ___sys_sendmsg net/socket.c:2384 [inline] __sys_sendmsg+0x1ed/0x290 net/socket.c:2430 __do_sys_sendmsg net/socket.c:2439 [inline] __se_sys_sendmsg net/socket.c:2437 [inline] __x64_sys_sendmsg+0x7f/0x90 net/socket.c:2437 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a679 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:00007efdb7fcbc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a679 RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007efdb7fcc6d4 R13: 00000000004c96b9 R14: 00000000004e13a8 R15: 00000000ffffffff