=====================================
[ BUG: bad unlock balance detected! ]
4.9.75-gb54d99a #8 Not tainted
-------------------------------------
syz-executor4/10605 is trying to release lock (mrt_lock) at:
[<ffffffff834e6574>] ipmr_mfc_seq_stop+0xe4/0x140 net/ipv6/ip6mr.c:553
but there are no more locks to release!

other info that might help us debug this:
2 locks held by syz-executor4/10605:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d20bf>] __fdget_pos+0x9f/0xc0 fs/file.c:781
 #1:  (&p->lock){+.+.+.}, at: [<ffffffff815e74bd>] seq_read+0xdd/0x1290 fs/seq_file.c:178

stack backtrace:
CPU: 1 PID: 10605 Comm: syz-executor4 Not tainted 4.9.75-gb54d99a #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8297800 ffffffff81d93049 ffffffff849b67b8 ffff8801d6b9c800
 ffffffff834e6574 ffffffff849b67b8 ffff8801d6b9d088 ffff8801d8297830
 ffffffff81236bf4 dffffc0000000000 ffffffff849b67b8 00000000ffffffff
Call Trace:
 [<ffffffff81d93049>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d93049>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81236bf4>] print_unlock_imbalance_bug+0x174/0x1a0 kernel/locking/lockdep.c:3398
 [<ffffffff8123f6c8>] __lock_release kernel/locking/lockdep.c:3540 [inline]
 [<ffffffff8123f6c8>] lock_release+0x6f8/0xb80 kernel/locking/lockdep.c:3775
 [<ffffffff838b05fa>] __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 [<ffffffff838b05fa>] _raw_read_unlock+0x1a/0x50 kernel/locking/spinlock.c:255
 [<ffffffff834e6574>] ipmr_mfc_seq_stop+0xe4/0x140 net/ipv6/ip6mr.c:553
 [<ffffffff815e4477>] traverse+0x3a7/0x900 fs/seq_file.c:148
 [<ffffffff815e7bca>] seq_read+0x7ea/0x1290 fs/seq_file.c:195
 [<ffffffff816c0b5f>] proc_reg_read+0xef/0x170 fs/proc/inode.c:202
 [<ffffffff8156b481>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff8156f2f0>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff8156f2f0>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff8156f5a4>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff8156f6c6>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff81572bb7>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff81572bb7>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838b0aa8>] entry_SYSCALL_64_fastpath+0x23/0xe2
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10645 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10653 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10670 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10705 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10728 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10766 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10803 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10823 comm=syz-executor4
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10848 comm=syz-executor4