rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=cf6/1/0x4000000000000004 softirq=12803/12804 fqs=5249 
	(t=10502 jiffies g=14513 q=3155)
NMI backtrace for cpu 0
CPU: 0 PID: 3464 Comm: ion_system_heap Not tainted 5.3.0-rc8+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 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:164 [inline]
 rcu_dump_cpu_stacks+0x183/0x1cf 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.cold+0x4dd/0xc13 kernel/rcu/tree.c:2183
 update_process_times+0x32/0x80 kernel/time/timer.c:1639
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
RIP: 0010:__list_add_valid+0x2b/0xa0 lib/list_debug.c:23
Code: b8 00 00 00 00 00 fc ff df 55 48 89 e5 41 55 49 89 fd 48 8d 7a 08 41 54 49 89 d4 48 89 fa 48 83 ec 08 48 c1 ea 03 80 3c 02 00 <75> 52 49 8b 54 24 08 48 39 f2 0f 85 5a 01 00 00 48 b8 00 00 00 00
RSP: 0018:ffff8880ae808e50 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff888097d49078 RCX: ffffffff85c67051
RDX: 1ffff11012fa9223 RSI: ffff888097d49110 RDI: ffff888097d49118
RBP: ffff8880ae808e68 R08: ffff88809ca0c380 R09: 0000000000000000
R10: fffffbfff134afaf R11: ffff88809ca0c380 R12: ffff888097d49110
R13: ffff888097d49078 R14: ffff888097d49118 R15: ffff888097d49110
 __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+0x66d/0xa20 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+0x1e7/0x19d0 net/sched/sch_generic.c:379
 __dev_xmit_skb net/core/dev.c:3533 [inline]
 __dev_queue_xmit+0x16f1/0x3650 net/core/dev.c:3838
 dev_queue_xmit+0x18/0x20 net/core/dev.c:3902
 br_dev_queue_push_xmit+0x3f3/0x5c0 net/bridge/br_forward.c:52
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 br_forward_finish+0xfa/0x400 net/bridge/br_forward.c:65
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 __br_forward+0x641/0xb00 net/bridge/br_forward.c:109
 deliver_clone+0x61/0xc0 net/bridge/br_forward.c:125
 maybe_deliver+0x2c7/0x390 net/bridge/br_forward.c:181
 br_flood+0x13a/0x3d0 net/bridge/br_forward.c:223
 br_dev_xmit+0x98c/0x15a0 net/bridge/br_device.c:100
 __netdev_start_xmit include/linux/netdevice.h:4406 [inline]
 netdev_start_xmit include/linux/netdevice.h:4420 [inline]
 xmit_one net/core/dev.c:3280 [inline]
 dev_hard_start_xmit+0x1a3/0x9c0 net/core/dev.c:3296
 __dev_queue_xmit+0x2b15/0x3650 net/core/dev.c:3869
 dev_queue_xmit+0x18/0x20 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+0xf58/0x2520 net/ipv6/ip6_output.c:116
 __ip6_finish_output+0x444/0xa50 net/ipv6/ip6_output.c:142
 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x235/0x7c0 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ndisc_send_skb+0xf29/0x1450 net/ipv6/ndisc.c:504
 ndisc_send_rs+0x134/0x6d0 net/ipv6/ndisc.c:698
 addrconf_rs_timer+0x30f/0x680 net/ipv6/addrconf.c:3879
 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322
 expire_timers kernel/time/timer.c:1366 [inline]
 __run_timers kernel/time/timer.c:1685 [inline]
 __run_timers kernel/time/timer.c:1653 [inline]
 run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:537 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 </IRQ>
RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:66
Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
RSP: 0018:ffff88809c887ad8 EFLAGS: 00010246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: ffffea0000fe67c0 RCX: 000000000001dd40
RDX: 0000000000020000 RSI: 0000000000000000 RDI: ffffc90015dc22c0
RBP: ffff88809c887af8 R08: fffff52002bbc000 R09: ffffc90015dc0000
R10: fffff52002bbbfff R11: ffffc90015ddffff R12: ffffc90015dc0000
R13: 0000000000020000 R14: 0000000000000000 R15: ffff88809c887d08
 memset include/linux/string.h:344 [inline]
 ion_heap_clear_pages+0x49/0x70 drivers/staging/android/ion/ion_heap.c:106
 ion_heap_sglist_zero+0x210/0x270 drivers/staging/android/ion/ion_heap.c:123
 ion_heap_buffer_zero+0xf5/0x150 drivers/staging/android/ion/ion_heap.c:145
 ion_system_heap_free+0x1eb/0x250 drivers/staging/android/ion/ion_system_heap.c:163
 ion_buffer_destroy+0x159/0x2d0 drivers/staging/android/ion/ion.c:122
 ion_heap_deferred_free+0x29d/0x630 drivers/staging/android/ion/ion_heap.c:239
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352