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SubjectINFO: rcu detected stall in mld_ifc_timer_expire

syzbot found the following crash on:

HEAD commit: 3b47fd5c Merge tag 'nfs-for-5.3-4' of git://git.linux-nfs...
git tree: upstream
console output:
kernel config:
dashboard link:
compiler: clang version 9.0.0 (/home/glider/llvm/clang
syz repro:
C reproducer:

Bisection is inconclusive: the bug happens on the oldest tested release.

bisection log:
console output:

IMPORTANT: if you fix the bug, please add the following tag to the commit:

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (10500 ticks this GP) idle=d6e/0/0x3 softirq=9083/9083 fqs=0
(t=10501 jiffies g=6617 q=143)
rcu: rcu_preempt kthread starved for 10502 jiffies! g6617 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt I29080 10 2 0x80004000
Call Trace:
context_switch kernel/sched/core.c:3254 [inline]
__schedule+0x877/0xc50 kernel/sched/core.c:3880
schedule+0x131/0x1e0 kernel/sched/core.c:3947
schedule_timeout+0x14f/0x240 kernel/time/timer.c:1807
rcu_gp_fqs_loop kernel/rcu/tree.c:1611 [inline]
rcu_gp_kthread+0xef8/0x1790 kernel/rcu/tree.c:1768
kthread+0x332/0x350 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0-rc7+ #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+0x1d8/0x2f8 lib/dump_stack.c:113
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:2736 [inline]
rcu_sched_clock_irq+0xb95/0x16d0 kernel/rcu/tree.c:2183
update_process_times+0x134/0x190 kernel/time/timer.c:1639
tick_sched_handle kernel/time/tick-sched.c:167 [inline]
tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1296
__run_hrtimer kernel/time/hrtimer.c:1389 [inline]
__hrtimer_run_queues+0x403/0x850 kernel/time/hrtimer.c:1451
hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1509
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1106 [inline]
smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1131
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
RIP: 0010:__list_add_valid+0xc/0xc0 lib/list_debug.c:22
Code: 89 e5 53 48 89 fb e8 83 d6 1f fe 48 c7 c7 56 5a 45 88 48 89 de e8 44
fd ff ff 5b 5d c3 90 55 48 89 e5 41 57 41 56 41 55 41 54 <53> 49 89 d6 49
89 f4 49 89 ff 49 bd 00 00 00 00 00 fc ff df 48 8d
RSP: 0018:ffff8880aea09730 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11012f53d0a RBX: 1ffff11012f53d0b RCX: ffffffff88875a00
RDX: ffff888097a9e850 RSI: ffff888097a9e850 RDI: ffff888097a9e7b8
RBP: ffff8880aea09750 R08: ffffffff860c4d6a R09: 0000000000000000
R10: fffffbfff117be8d R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888097a9e4c0 R14: ffff888097a9e850 R15: ffff888097a9e840
__list_add include/linux/list.h:60 [inline]
list_add_tail include/linux/list.h:93 [inline]
list_move_tail include/linux/list.h:214 [inline]
hhf_dequeue+0x535/0xaa0 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+0x217/0x1b30 net/sched/sch_generic.c:379
__dev_xmit_skb net/core/dev.c:3533 [inline]
__dev_queue_xmit+0x1161/0x3020 net/core/dev.c:3838
dev_queue_xmit+0x17/0x20 net/core/dev.c:3902
neigh_hh_output include/net/neighbour.h:500 [inline]
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0xff2/0x13d0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x693/0x910 net/ipv6/ip6_output.c:142
ip6_finish_output+0x52/0x1e0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x26f/0x390 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:305 [inline]
mld_sendpack+0x770/0xb90 net/ipv6/mcast.c:1682
mld_send_cr net/ipv6/mcast.c:1978 [inline]
mld_ifc_timer_expire+0x820/0xb70 net/ipv6/mcast.c:2477
call_timer_fn+0x95/0x170 kernel/time/timer.c:1322
expire_timers kernel/time/timer.c:1366 [inline]
__run_timers+0x79e/0x970 kernel/time/timer.c:1685
run_timer_softirq+0x4a/0x90 kernel/time/timer.c:1698
__do_softirq+0x333/0x7c4 arch/x86/include/asm/paravirt.h:778
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x227/0x230 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:537 [inline]
smp_apic_timer_interrupt+0x113/0x280 arch/x86/kernel/apic/apic.c:1133
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 30 fa eb ae 89 d9 80 e1 07 80 c1 03 38 c1 7c ba 48 89 df e8 f4 b0 30
fa eb b0 90 90 e9 07 00 00 00 0f 00 2d 96 b0 46 00 fb f4 <c3> 90 e9 07 00
00 00 0f 00 2d 86 b0 46 00 f4 c3 90 90 55 48 89 e5
RSP: 0018:ffffffff88807dc0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11150f3 RBX: ffffffff88875a00 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffffffff812b7a1a RDI: ffffffff877bd46a
RBP: ffffffff88807dc8 R08: ffffffff81790e14 R09: fffffbfff110eb41
R10: fffffbfff110eb41 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffffffff110eb40 R14: dffffc0000000000 R15: 0000000000000000
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
default_idle_call+0x59/0xa0 kernel/sched/idle.c:94
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x140/0x6d0 kernel/sched/idle.c:263
cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:354
rest_init+0x29d/0x2b0 init/main.c:451
start_kernel+0x6f5/0x7f6 init/main.c:785
x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:472
x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:453
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

This bug is generated by a bot. It may contain errors.
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For information about bisection process see:
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