=============================
WARNING: suspicious RCU usage
4.14.96+ #20 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1590 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by swapper/0/0:
 #0:  (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [<ffffffffa9062996>] lockdep_copy_map include/linux/lockdep.h:174 [inline]
 #0:  (((&net->ipv6.ip6_fib_timer))){+.-.}, at: [<ffffffffa9062996>] call_timer_fn+0xc6/0x680 kernel/time/timer.c:1269
 #1:  (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [<ffffffffaa4fbbd3>] spin_lock_bh include/linux/spinlock.h:322 [inline]
 #1:  (&(&net->ipv6.fib6_gc_lock)->rlock){+.-.}, at: [<ffffffffaa4fbbd3>] fib6_run_gc+0x93/0x2a0 net/ipv6/ip6_fib.c:1938
 #2:  (rcu_read_lock){....}, at: [<ffffffffaa4f3170>] __fib6_clean_all+0x0/0x230 net/ipv6/ip6_fib.c:1823
 #3:  (&tb->tb6_lock){++--}, at: [<ffffffffaa4f324e>] __fib6_clean_all+0xde/0x230 net/ipv6/ip6_fib.c:1837

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.96+ #20
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x10e lib/dump_stack.c:53
 fib6_del+0x8c2/0xbe0 net/ipv6/ip6_fib.c:1590
 fib6_clean_node+0x270/0x440 net/ipv6/ip6_fib.c:1777
 fib6_walk_continue+0x3a5/0x5f0 net/ipv6/ip6_fib.c:1703
 fib6_walk+0x8d/0xe0 net/ipv6/ip6_fib.c:1748
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:1822
 __fib6_clean_all+0xf5/0x230 net/ipv6/ip6_fib.c:1838
 fib6_clean_all net/ipv6/ip6_fib.c:1849 [inline]
 fib6_run_gc+0x104/0x2a0 net/ipv6/ip6_fib.c:1947
 call_timer_fn+0x14a/0x680 kernel/time/timer.c:1279
 expire_timers+0x216/0x4b0 kernel/time/timer.c:1318
 __run_timers kernel/time/timer.c:1634 [inline]
 run_timer_softirq+0x1eb/0x5d0 kernel/time/timer.c:1647
 __do_softirq+0x234/0x9ca kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x114/0x150 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x185/0x620 arch/x86/kernel/apic/apic.c:1064
 apic_timer_interrupt+0x84/0x90 arch/x86/entry/entry_64.S:787
 </IRQ>
RIP: 0010:native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:58
RSP: 0018:ffffffffab207d48 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000007 RBX: ffffffffab62ffc8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffab231a2c
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffffab231200 R15: dffffc0000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
 default_idle+0x50/0x390 arch/x86/kernel/process.c:564
 cpuidle_idle_call kernel/sched/idle.c:159 [inline]
 do_idle+0x2e6/0x390 kernel/sched/idle.c:268
 cpu_startup_entry+0xc6/0xd0 kernel/sched/idle.c:374
 start_kernel+0x712/0x74a init/main.c:710
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240
netlink: 8 bytes leftover after parsing attributes in process `syz-executor3'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor3'.