===================================== WARNING: bad unlock balance detected! 4.16.0-rc2+ #323 Not tainted ------------------------------------- syzkaller649676/4162 is trying to release lock (rcu_read_lock_bh) at: [] rcu_read_unlock_bh include/linux/rcupdate.h:722 [inline] [] hashlimit_mt_common.isra.10+0x1beb/0x2610 net/netfilter/xt_hashlimit.c:777 but there are no more locks to release! other info that might help us debug this: 4 locks held by syzkaller649676/4162: #0: (rcu_read_lock){....}, at: [<0000000037b72bad>] sock_lock_init net/core/sock.c:1421 [inline] #0: (rcu_read_lock){....}, at: [<0000000037b72bad>] sk_alloc+0xa5c/0x1440 net/core/sock.c:1534 #1: ((&ndev->rs_timer)){+.-.}, at: [<000000003848bf14>] lockdep_copy_map include/linux/lockdep.h:178 [inline] #1: ((&ndev->rs_timer)){+.-.}, at: [<000000003848bf14>] call_timer_fn+0x1c6/0x820 kernel/time/timer.c:1316 #2: (rcu_read_lock){....}, at: [<000000003e233648>] ip6_nd_hdr net/ipv6/ndisc.c:449 [inline] #2: (rcu_read_lock){....}, at: [<000000003e233648>] ndisc_send_skb+0x826/0x1370 net/ipv6/ndisc.c:485 #3: (rcu_read_lock){....}, at: [<000000002b621250>] nf_hook.constprop.27+0x0/0x830 net/ipv6/ndisc.c:387 stack backtrace: CPU: 1 PID: 4162 Comm: syzkaller649676 Not tainted 4.16.0-rc2+ #323 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_unlock_imbalance_bug+0x12f/0x140 kernel/locking/lockdep.c:3484 __lock_release kernel/locking/lockdep.c:3691 [inline] lock_release+0x6fe/0xa40 kernel/locking/lockdep.c:3939 rcu_lock_release include/linux/rcupdate.h:249 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:724 [inline] hashlimit_mt_common.isra.10+0x1c08/0x2610 net/netfilter/xt_hashlimit.c:777 hashlimit_mt+0x78/0x90 net/netfilter/xt_hashlimit.c:846 ip6t_do_table+0x98d/0x1a30 net/ipv6/netfilter/ip6_tables.c:319 ip6table_filter_hook+0x65/0x80 net/ipv6/netfilter/ip6table_filter.c:41 nf_hook_entry_hookfn include/linux/netfilter.h:120 [inline] nf_hook_slow+0xba/0x1a0 net/netfilter/core.c:483 nf_hook.constprop.27+0x3f6/0x830 include/linux/netfilter.h:243 NF_HOOK include/linux/netfilter.h:286 [inline] ndisc_send_skb+0xa51/0x1370 net/ipv6/ndisc.c:491 ndisc_send_rs+0x126/0x670 net/ipv6/ndisc.c:685 addrconf_rs_timer+0x363/0x6b0 net/ipv6/addrconf.c:3769 call_timer_fn+0x228/0x820 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x7ee/0xb70 kernel/time/timer.c:1666 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1cc/0x200 kernel/softirq.c:405 exiting_irq arch/x86/include/asm/apic.h:541 [inline] smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052 apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:796 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:777 [inline] RIP: 0010:lock_is_held_type+0x18b/0x210 kernel/locking/lockdep.c:3960 RSP: 0018:ffff8801d7997848 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff12 RAX: dffffc0000000000 RBX: 0000000000000282 RCX: ffffffff8437b016 RDX: 1ffffffff0d592d5 RSI: ffffffff86b60cf8 RDI: 0000000000000282 RBP: ffff8801d7997868 R08: 1ffff1003af32e51 R09: 0000000000000002 R10: ffff8801d7997748 R11: 0000000000000000 R12: ffff8801b3e7a080 R13: 0000000000000000 R14: dffffc0000000000 R15: ffffffff86b5eb20 lock_is_held include/linux/lockdep.h:344 [inline] task_css include/linux/cgroup.h:477 [inline] task_cls_classid include/net/cls_cgroup.h:38 [inline] sock_update_classid include/net/cls_cgroup.h:49 [inline] sk_alloc+0xf37/0x1440 net/core/sock.c:1546 inet6_create+0x44d/0x10f0 net/ipv6/af_inet6.c:183 __sock_create+0x4d4/0x850 net/socket.c:1285 sock_create net/socket.c:1325 [inline] SYSC_socket net/socket.c:1355 [inline] SyS_socket+0xeb/0x1d0 net/socket.c:1335 do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x447d39 RSP: 002b:00007ffc852951b8 EFLAGS: 00000207 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 00007ffc85295270 RCX: 0000000000447d39 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 000000000000000a RBP: 0000000000000000 R08: 00007ffc852951d0 R09: 00007ffc852951d0 R10: 00007ffc852951d0 R11: 0000000000000207 R12: 0000000000409570 R13: 0000000000409600 R14: 0000000000000000 R15: 0000000000000000