INFO: rcu detected stall in rds_connect

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: rcu detected stall in rds_connect_worker (2) net				3	1214d	1225d	0/26	auto-closed as invalid on 2021/03/28 19:53

rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10499 ticks this GP) idle=526/1/0x4000000000000002 softirq=37851/37851 fqs=591 (t=10502 jiffies g=70721 q=69) rcu: rcu_preempt kthread starved for 9320 jiffies! g70721 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt I28768 10 2 0x80004000 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4163 schedule_timeout+0x35c/0x850 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline] rcu_gp_kthread+0x9bf/0x1960 kernel/rcu/tree.c:1836 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 0 CPU: 0 PID: 3712 Comm: kworker/u4:5 Not tainted 5.7.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: krdsd rds_connect_worker Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x19b/0x1e5 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:3225 [inline] rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296 update_process_times+0x25/0x60 kernel/time/timer.c:1727 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline] smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 </IRQ> RIP: 0010:sfq_dequeue+0x19f/0xcc0 net/sched/sch_sfq.c:492 Code: 66 44 03 a5 e2 02 00 00 66 44 89 63 1a 48 8b 9d 28 03 00 00 48 8d 7b 12 48 89 f8 48 c1 e8 03 42 0f b6 14 30 48 89 f8 83 e0 07 <83> c0 01 38 d0 7c 08 84 d2 0f 85 2b 0a 00 00 44 0f b7 63 12 48 8b RSP: 0018:ffffc9000cfdeed0 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000002 RBX: ffff88805c555bc8 RCX: ffffffff86465097 RDX: 0000000000000000 RSI: ffffffff86464fd2 RDI: ffff88805c555bda RBP: ffff88809e6ab000 R08: ffff888099e7a3c0 R09: fffff520019fbdb8 R10: 0000000000000003 R11: fffff520019fbdb7 R12: 0000000000000000 R13: ffff88805c555be2 R14: dffffc0000000000 R15: 000000000000007f dequeue_skb net/sched/sch_generic.c:263 [inline] qdisc_restart net/sched/sch_generic.c:366 [inline] __qdisc_run+0x1ac/0x17b0 net/sched/sch_generic.c:384 __dev_xmit_skb net/core/dev.c:3704 [inline] __dev_queue_xmit+0x1d07/0x30a0 net/core/dev.c:4021 neigh_hh_output include/net/neighbour.h:499 [inline] neigh_output include/net/neighbour.h:508 [inline] ip6_finish_output2+0xfb5/0x25b0 net/ipv6/ip6_output.c:117 __ip6_finish_output+0x442/0xab0 net/ipv6/ip6_output.c:143 ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x239/0x810 net/ipv6/ip6_output.c:176 dst_output include/net/dst.h:435 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip6_xmit+0xe1a/0x2090 net/ipv6/ip6_output.c:280 inet6_csk_xmit+0x339/0x610 net/ipv6/inet6_connection_sock.c:135 __tcp_transmit_skb+0x1a07/0x3760 net/ipv4/tcp_output.c:1238 __tcp_send_ack.part.0+0x3a9/0x590 net/ipv4/tcp_output.c:3779 __tcp_send_ack net/ipv4/tcp_output.c:3785 [inline] tcp_send_ack+0x7d/0xa0 net/ipv4/tcp_output.c:3785 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6035 [inline] tcp_rcv_state_process+0x36e4/0x4c80 net/ipv4/tcp_input.c:6204 tcp_v6_do_rcv+0x7d2/0x1290 net/ipv6/tcp_ipv6.c:1463 sk_backlog_rcv include/net/sock.h:996 [inline] __release_sock+0x134/0x3a0 net/core/sock.c:2460 release_sock+0x54/0x1b0 net/core/sock.c:2976 inet_stream_connect+0x76/0xa0 net/ipv4/af_inet.c:720 rds_tcp_conn_path_connect+0x620/0x880 net/rds/tcp_connect.c:172 rds_connect_worker+0x1a5/0x2c0 net/rds/threads.c:176 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352