syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3700/1:b..l
	(detected by 0, t=10502 jiffies, g=31869, q=306)
task:kworker/0:7     state:R  running task     stack:23896 pid: 3700 ppid:     2 flags:0x00004000
Workqueue: mld mld_ifc_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x16c/0x1f0 kernel/softirq.c:390
Code: 8a e8 d8 b2 e6 08 65 66 8b 05 50 19 b6 7e 66 85 c0 75 57 bf 01 00 00 00 e8 61 ed 09 00 e8 0c 5b 39 00 fb 65 8b 05 3c f0 b4 7e <85> c0 75 05 e8 0b 0d b3 ff 48 c7 44 24 20 0e 36 e0 45 49 c7 04 1c
RSP: 0018:ffffc90003187760 EFLAGS: 00000286
RAX: 0000000000000000 RBX: 1ffff92000630ef0 RCX: ffffffff81631a88
RDX: dffffc0000000000 RSI: ffffffff8a8b2a20 RDI: ffffffff8ad90100
RBP: ffffc90003187810 R08: dffffc0000000000 R09: fffffbfff20e222a
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff92000630ef4 R14: ffffc900031877a0 R15: 0000000000000200
 rcu_read_unlock_bh include/linux/rcupdate.h:809 [inline]
 ip6_finish_output2+0x103e/0x15a0 net/ipv6/ip6_output.c:131
 dst_output include/net/dst.h:443 [inline]
 NF_HOOK+0x166/0x4f0 include/linux/netfilter.h:302
 mld_sendpack+0x70e/0xc10 net/ipv6/mcast.c:1820
 mld_send_cr net/ipv6/mcast.c:2121 [inline]
 mld_ifc_work+0x7d7/0xc90 net/ipv6/mcast.c:2653
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10235 jiffies! g31869 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562