=====================================
[ BUG: bad unlock balance detected! ]
4.4.113-g202e079 #1 Not tainted
-------------------------------------
syz-executor0/21368 is trying to release lock (mrt_lock) at:
[<ffffffff833c5524>] 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 syz-executor0/21368:
 #0:  (&p->lock){+.+.+.}, at: [<ffffffff8158c14d>] seq_read+0xdd/0x1270 fs/seq_file.c:178

stack backtrace:
CPU: 0 PID: 21368 Comm: syz-executor0 Not tainted 4.4.113-g202e079 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 4e7e645eb639eedb ffff8800b7ae7930 ffffffff81d0278d
 ffffffff84771c18 ffff8801d3b14740 ffffffff833c5524 ffffffff84771c18
 ffff8801d3b14f88 ffff8800b7ae7960 ffffffff81232314 dffffc0000000000
Call Trace:
 [<ffffffff81d0278d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0278d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81232314>] print_unlock_imbalance_bug+0x174/0x1a0 kernel/locking/lockdep.c:3266
 [<ffffffff8123d1aa>] __lock_release kernel/locking/lockdep.c:3408 [inline]
 [<ffffffff8123d1aa>] lock_release+0x72a/0xc10 kernel/locking/lockdep.c:3611
 [<ffffffff8377145a>] __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 [<ffffffff8377145a>] _raw_read_unlock+0x1a/0x50 kernel/locking/spinlock.c:255
 [<ffffffff833c5524>] ipmr_mfc_seq_stop+0xe4/0x140 net/ipv6/ip6mr.c:553
 [<ffffffff8158caf0>] seq_read+0xa80/0x1270 fs/seq_file.c:283
 [<ffffffff8166479f>] proc_reg_read+0xef/0x170 fs/proc/inode.c:202
 [<ffffffff8151c561>] do_loop_readv_writev+0x141/0x1e0 fs/read_write.c:680
 [<ffffffff8151e8bd>] do_readv_writev+0x5dd/0x6e0 fs/read_write.c:810
 [<ffffffff8151ea38>] vfs_readv+0x78/0xb0 fs/read_write.c:834
 [<ffffffff815212a9>] SYSC_preadv fs/read_write.c:912 [inline]
 [<ffffffff815212a9>] SyS_preadv+0x199/0x230 fs/read_write.c:898
 [<ffffffff83771b5f>] entry_SYSCALL_64_fastpath+0x1c/0x98
audit_printk_skb: 10 callbacks suppressed
audit: type=1326 audit(1517169182.090:65): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=23087 comm="syz-executor3" exe="/root/syz-executor3" sig=31 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x0
audit: type=1326 audit(1517169182.160:66): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=23109 comm="syz-executor3" exe="/root/syz-executor3" sig=31 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x0
audit: type=1326 audit(1517169182.250:67): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=23144 comm="syz-executor3" exe="/root/syz-executor3" sig=31 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x0
audit: type=1400 audit(1517169184.150:68): avc:  denied  { setattr } for  pid=23849 comm="syz-executor7" name="sockcreate" dev="proc" ino=36992 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=file permissive=1