INFO: rcu_preempt self-detected stall on CPU
	1-...: (10499 ticks this GP) idle=3e6/140000000000002/0 softirq=12310/12310 fqs=6 
	 (t=10500 jiffies g=1902 c=1901 q=746)
rcu_preempt kthread starved for 10482 jiffies! g1902 c1901 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
rcu_preempt     R  running task    29984     8      2 0x80000000
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746
 rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
NMI backtrace for cpu 1
CPU: 1 PID: 7836 Comm: syz-executor.2 Not tainted 4.14.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:158 [inline]
 rcu_dump_cpu_stacks+0x16d/0x1b8 kernel/rcu/tree.c:1396
 print_cpu_stall kernel/rcu/tree.c:1542 [inline]
 check_cpu_stall kernel/rcu/tree.c:1610 [inline]
 __rcu_pending kernel/rcu/tree.c:3390 [inline]
 rcu_pending kernel/rcu/tree.c:3452 [inline]
 rcu_check_callbacks.cold+0x490/0xdaa kernel/rcu/tree.c:2792
 update_process_times+0x29/0x60 kernel/time/timer.c:1590
 tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165
 tick_sched_timer+0x3e/0x120 kernel/time/tick-sched.c:1223
 __run_hrtimer kernel/time/hrtimer.c:1223 [inline]
 __hrtimer_run_queues+0x25c/0xbb0 kernel/time/hrtimer.c:1287
 hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
 smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100
 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:queued_write_lock_slowpath+0x80/0x1d0 kernel/locking/qrwlock.c:130
RSP: 0018:ffff8880aeb07810 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 00000000000000ff RBX: ffffffff8877d7b0 RCX: 0000000005b5d530
RDX: 0000000000000000 RSI: ffff88808b9e0f70 RDI: ffffffff8877d7b0
RBP: ffffffff8877d7b4 R08: 0000000000007216 R09: ffffffff8a094930
R10: ffff88808b9e0f70 R11: ffff88808b9e0600 R12: fffffbfff10efaf6
R13: 0000000000000000 R14: 0000000000000001 R15: ffff8880889c0940
 queued_write_lock include/asm-generic/qrwlock.h:134 [inline]
 do_raw_write_lock+0xc2/0x1d0 kernel/locking/spinlock_debug.c:203
 neigh_forced_gc net/core/neighbour.c:176 [inline]
 neigh_alloc net/core/neighbour.c:315 [inline]
 __neigh_create+0xb27/0x1980 net/core/neighbour.c:499
 ip6_finish_output2+0xa8e/0x2150 net/ipv6/ip6_output.c:117
 ip6_finish_output+0x4d9/0xaf0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip6_output+0x1c9/0x650 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:462 [inline]
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ndisc_send_skb+0xb56/0x11e0 net/ipv6/ndisc.c:483
 ndisc_send_rs+0x125/0x630 net/ipv6/ndisc.c:677
 addrconf_rs_timer+0x289/0x5a0 net/ipv6/addrconf.c:3757
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279
 expire_timers kernel/time/timer.c:1318 [inline]
 __run_timers kernel/time/timer.c:1636 [inline]
 __run_timers kernel/time/timer.c:1604 [inline]
 run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649
 __do_softirq+0x254/0x9bf kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x15b/0x1a0 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x3d/0x50 kernel/kcov.c:87
RSP: 0018:ffff88805c9af5c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc9000a861000
RDX: 000000000003ffff RSI: ffffffff8184104d RDI: 000000005c12b025
RBP: ffffea0001704ac0 R08: 0000000000007573 R09: ffffffff8a096418
R10: ffff88808b9e0ed0 R11: ffff88808b9e0600 R12: effffffff47da800
R13: ffffea0001704ac0 R14: 000000000005c12b R15: ffff8880a5139ca0
 pte_val arch/x86/include/asm/paravirt.h:384 [inline]
 pte_to_swp_entry include/linux/swapops.h:72 [inline]
 remove_migration_pte+0x3ad/0xb80 mm/migrate.c:240
 rmap_walk_anon+0x337/0x8f0 mm/rmap.c:1775
 rmap_walk_locked+0x10a/0x180 mm/rmap.c:1856
 remove_migration_ptes+0xa1/0xf0 mm/migrate.c:297
 remap_page+0x7a/0xe0 mm/huge_memory.c:2308
 __split_huge_page mm/huge_memory.c:2411 [inline]
 split_huge_page_to_list+0x12eb/0x1f40 mm/huge_memory.c:2649
 split_huge_page include/linux/huge_mm.h:141 [inline]
 madvise_free_huge_pmd+0x78f/0x9e0 mm/huge_memory.c:1642
 madvise_free_pte_range+0x614/0x19d0 mm/madvise.c:325
 walk_pmd_range mm/pagewalk.c:51 [inline]
 walk_pud_range mm/pagewalk.c:109 [inline]
 walk_p4d_range mm/pagewalk.c:135 [inline]
 walk_pgd_range mm/pagewalk.c:161 [inline]
 __walk_page_range+0xb2b/0x1300 mm/pagewalk.c:254
 walk_page_range+0x149/0x2f0 mm/pagewalk.c:331
 madvise_free_page_range.isra.0+0x9b/0xc0 mm/madvise.c:454
 madvise_free_single_vma+0x299/0x410 mm/madvise.c:481
 madvise_dontneed_free mm/madvise.c:565 [inline]
 madvise_vma mm/madvise.c:688 [inline]
 SYSC_madvise mm/madvise.c:863 [inline]
 SyS_madvise+0x4f8/0x1270 mm/madvise.c:791
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007fa7fe24cc78 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fa7fe24d6d4 RCX: 000000000045c849
RDX: 0000000000000008 RSI: 0000000000600000 RDI: 00000000200d9000
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000727 R14: 00000000004c9ee6 R15: 000000000076bf0c
INFO: rcu_sched detected stalls on CPUs/tasks:
	1-...: (10501 ticks this GP) idle=3e6/140000000000002/0 softirq=12310/12310 fqs=6 
	(detected by 0, t=10567 jiffies, g=1274, c=1273, q=20)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7836 Comm: syz-executor.2 Not tainted 4.14.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808b9e0600 task.stack: ffff88805c9a8000
RIP: 0010:kvm_sched_clock_read+0xc/0x10 arch/x86/kernel/kvmclock.c:101
RSP: 0018:ffff8880aeb076d0 EFLAGS: 00000002
RAX: 000000382fd73d38 RBX: ffff8880aeb1f5f0 RCX: 0000000000000004
RDX: 0000000013a6a4e5 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff88808b9e0600 R08: 00000038f9e6d499 R09: ffff88821fff7048
R10: ffff88821fff7050 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fa7fe24d700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd9ee6e970 CR3: 0000000081890000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 paravirt_sched_clock arch/x86/include/asm/paravirt.h:175 [inline]
 sched_clock+0x2a/0x40 arch/x86/kernel/tsc.c:228
 sched_clock_cpu+0x18/0x1b0 kernel/sched/clock.c:363
 irqtime_account_irq+0x63/0x280 kernel/sched/cputime.c:63
 account_irq_exit_time include/linux/vtime.h:114 [inline]
 irq_exit+0x48/0x1a0 kernel/softirq.c:406
 irq_work_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:823
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:queued_write_lock_slowpath+0x80/0x1d0 kernel/locking/qrwlock.c:130
RSP: 0018:ffff8880aeb07810 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff09
RAX: 00000000000000ff RBX: ffffffff8877d7b0 RCX: 0000000005b5d530
RDX: 0000000000000000 RSI: ffff88808b9e0f70 RDI: ffffffff8877d7b0
RBP: ffffffff8877d7b4 R08: 0000000000007216 R09: ffffffff8a094930
R10: ffff88808b9e0f70 R11: ffff88808b9e0600 R12: fffffbfff10efaf6
R13: 0000000000000000 R14: 0000000000000001 R15: ffff8880889c0940
 queued_write_lock include/asm-generic/qrwlock.h:134 [inline]
 do_raw_write_lock+0xc2/0x1d0 kernel/locking/spinlock_debug.c:203
 neigh_forced_gc net/core/neighbour.c:176 [inline]
 neigh_alloc net/core/neighbour.c:315 [inline]
 __neigh_create+0xb27/0x1980 net/core/neighbour.c:499
 ip6_finish_output2+0xa8e/0x2150 net/ipv6/ip6_output.c:117
 ip6_finish_output+0x4d9/0xaf0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip6_output+0x1c9/0x650 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:462 [inline]
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ndisc_send_skb+0xb56/0x11e0 net/ipv6/ndisc.c:483
 ndisc_send_rs+0x125/0x630 net/ipv6/ndisc.c:677
 addrconf_rs_timer+0x289/0x5a0 net/ipv6/addrconf.c:3757
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279
 expire_timers kernel/time/timer.c:1318 [inline]
 __run_timers kernel/time/timer.c:1636 [inline]
 __run_timers kernel/time/timer.c:1604 [inline]
 run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649
 __do_softirq+0x254/0x9bf kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x15b/0x1a0 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x3d/0x50 kernel/kcov.c:87
RSP: 0018:ffff88805c9af5c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc9000a861000
RDX: 000000000003ffff RSI: ffffffff8184104d RDI: 000000005c12b025
RBP: ffffea0001704ac0 R08: 0000000000007573 R09: ffffffff8a096418
R10: ffff88808b9e0ed0 R11: ffff88808b9e0600 R12: effffffff47da800
R13: ffffea0001704ac0 R14: 000000000005c12b R15: ffff8880a5139ca0
 pte_val arch/x86/include/asm/paravirt.h:384 [inline]
 pte_to_swp_entry include/linux/swapops.h:72 [inline]
 remove_migration_pte+0x3ad/0xb80 mm/migrate.c:240
 rmap_walk_anon+0x337/0x8f0 mm/rmap.c:1775
 rmap_walk_locked+0x10a/0x180 mm/rmap.c:1856
 remove_migration_ptes+0xa1/0xf0 mm/migrate.c:297
 remap_page+0x7a/0xe0 mm/huge_memory.c:2308
 __split_huge_page mm/huge_memory.c:2411 [inline]
 split_huge_page_to_list+0x12eb/0x1f40 mm/huge_memory.c:2649
 split_huge_page include/linux/huge_mm.h:141 [inline]
 madvise_free_huge_pmd+0x78f/0x9e0 mm/huge_memory.c:1642
 madvise_free_pte_range+0x614/0x19d0 mm/madvise.c:325
 walk_pmd_range mm/pagewalk.c:51 [inline]
 walk_pud_range mm/pagewalk.c:109 [inline]
 walk_p4d_range mm/pagewalk.c:135 [inline]
 walk_pgd_range mm/pagewalk.c:161 [inline]
 __walk_page_range+0xb2b/0x1300 mm/pagewalk.c:254
 walk_page_range+0x149/0x2f0 mm/pagewalk.c:331
 madvise_free_page_range.isra.0+0x9b/0xc0 mm/madvise.c:454
 madvise_free_single_vma+0x299/0x410 mm/madvise.c:481
 madvise_dontneed_free mm/madvise.c:565 [inline]
 madvise_vma mm/madvise.c:688 [inline]
 SYSC_madvise mm/madvise.c:863 [inline]
 SyS_madvise+0x4f8/0x1270 mm/madvise.c:791
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007fa7fe24cc78 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fa7fe24d6d4 RCX: 000000000045c849
RDX: 0000000000000008 RSI: 0000000000600000 RDI: 00000000200d9000
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000727 R14: 00000000004c9ee6 R15: 000000000076bf0c
Code: 0d ba 3d da 7e 74 01 c3 e8 eb 8f d8 ff c3 90 eb ce 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 e8 bb ff ff ff 48 2b 05 64 f4 72 08 <c3> 0f 1f 00 41 54 bf 01 00 00 00 e8 b4 5f 16 00 e8 3f 75 d6 01 
rcu_sched kthread starved for 10550 jiffies! g1274 c1273 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
rcu_sched       R  running task    29984     9      2 0x80000000
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746
 rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.