=====================================
[ BUG: bad unlock balance detected! ]
4.9.67-gf26d3c7 #106 Not tainted
-------------------------------------
syzkaller997769/3309 is trying to release lock (mrt_lock) at:
[<ffffffff834dec54>] 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:
1 lock held by syzkaller997769/3309:
 #0:  (&p->lock){+.+.+.}, at: [<ffffffff815e4cdd>] seq_read+0xdd/0x1290 fs/seq_file.c:178

stack backtrace:
CPU: 1 PID: 3309 Comm: syzkaller997769 Not tainted 4.9.67-gf26d3c7 #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d1857918 ffffffff81d906e9 ffffffff849ae8f8 ffff8801d18b1800
 ffffffff834dec54 ffffffff849ae8f8 ffff8801d18b2088 ffff8801d1857948
 ffffffff812353f4 dffffc0000000000 ffffffff849ae8f8 00000000ffffffff
Call Trace:
 [<ffffffff81d906e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d906e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff812353f4>] print_unlock_imbalance_bug+0x174/0x1a0 kernel/locking/lockdep.c:3398
 [<ffffffff8123dec8>] __lock_release kernel/locking/lockdep.c:3540 [inline]
 [<ffffffff8123dec8>] lock_release+0x6f8/0xb80 kernel/locking/lockdep.c:3775
 [<ffffffff838a951a>] __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 [<ffffffff838a951a>] _raw_read_unlock+0x1a/0x50 kernel/locking/spinlock.c:255
 [<ffffffff834dec54>] ipmr_mfc_seq_stop+0xe4/0x140 net/ipv6/ip6mr.c:553
 [<ffffffff815e1c97>] traverse+0x3a7/0x900 fs/seq_file.c:148
 [<ffffffff815e53ea>] seq_read+0x7ea/0x1290 fs/seq_file.c:195
 [<ffffffff816be32f>] proc_reg_read+0xef/0x170 fs/proc/inode.c:202
 [<ffffffff815680d3>] __vfs_read+0x103/0x670 fs/read_write.c:452
 [<ffffffff8156be6e>] vfs_read+0x11e/0x380 fs/read_write.c:475
 [<ffffffff8156ff5f>] SYSC_pread64 fs/read_write.c:629 [inline]
 [<ffffffff8156ff5f>] SyS_pread64+0x13f/0x170 fs/read_write.c:616
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6