=====================================
WARNING: bad unlock balance detected!
4.15.0-rc9+ #278 Not tainted
-------------------------------------
syz-executor3/31667 is trying to release lock (mrt_lock) at:
[<0000000096eda695>] ipmr_mfc_seq_stop+0xe1/0x130 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-executor3/31667:
 #0:  (&p->lock){+.+.}, at: [<000000009342d8d0>] seq_read+0xd5/0x13d0 fs/seq_file.c:165

stack backtrace:
CPU: 1 PID: 31667 Comm: syz-executor3 Not tainted 4.15.0-rc9+ #278
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:3479
 __lock_release kernel/locking/lockdep.c:3685 [inline]
 lock_release+0x6fe/0xa40 kernel/locking/lockdep.c:3933
 __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 _raw_read_unlock+0x1a/0x30 kernel/locking/spinlock.c:248
 ipmr_mfc_seq_stop+0xe1/0x130 net/ipv6/ip6mr.c:553
 seq_read+0xc42/0x13d0 fs/seq_file.c:277
 proc_reg_read+0xef/0x170 fs/proc/inode.c:217
 do_loop_readv_writev fs/read_write.c:673 [inline]
 do_iter_read+0x3d2/0x5a0 fs/read_write.c:897
 vfs_readv+0x121/0x1c0 fs/read_write.c:959
 do_preadv+0x115/0x1a0 fs/read_write.c:1043
 SYSC_preadv fs/read_write.c:1093 [inline]
 SyS_preadv+0x30/0x40 fs/read_write.c:1088
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f4887778c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452f19
RDX: 0000000000000002 RSI: 000000002039e000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f48877799c0 R15: 0000000000000002
BUG: sleeping function called from invalid context at lib/usercopy.c:25
in_atomic(): 1, irqs_disabled(): 0, pid: 31667, name: syz-executor3
INFO: lockdep is turned off.
CPU: 1 PID: 31667 Comm: syz-executor3 Not tainted 4.15.0-rc9+ #278
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
 ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6060
 __might_sleep+0x95/0x190 kernel/sched/core.c:6013
 __might_fault+0xab/0x1d0 mm/memory.c:4532
 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25
 copy_to_user include/linux/uaccess.h:155 [inline]
 seq_read+0xcb4/0x13d0 fs/seq_file.c:279
 proc_reg_read+0xef/0x170 fs/proc/inode.c:217
 do_loop_readv_writev fs/read_write.c:673 [inline]
 do_iter_read+0x3d2/0x5a0 fs/read_write.c:897
 vfs_readv+0x121/0x1c0 fs/read_write.c:959
 do_preadv+0x115/0x1a0 fs/read_write.c:1043
 SYSC_preadv fs/read_write.c:1093 [inline]
 SyS_preadv+0x30/0x40 fs/read_write.c:1088
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f4887778c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452f19
RDX: 0000000000000002 RSI: 000000002039e000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f48877799c0 R15: 0000000000000002
WARNING: CPU: 1 PID: 31667 at lib/usercopy.c:26 _copy_to_user+0xb5/0xc0 lib/usercopy.c:26