=====================================
WARNING: bad unlock balance detected!
4.15.0-rc7+ #167 Not tainted
-------------------------------------
syz-executor7/4677 is trying to release lock (mrt_lock) at:
[<000000005fdd2b36>] 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-executor7/4677:
 #0:  (&p->lock){+.+.}, at: [<000000006069ab5f>] seq_read+0xd5/0x13d0 fs/seq_file.c:165

stack backtrace:
CPU: 0 PID: 4677 Comm: syz-executor7 Not tainted 4.15.0-rc7+ #167
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
 traverse+0x3bc/0xa00 fs/seq_file.c:135
 seq_read+0x96a/0x13d0 fs/seq_file.c:189
 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
 compat_readv+0x1bf/0x270 fs/read_write.c:1140
 do_compat_preadv64+0xd6/0x100 fs/read_write.c:1189
 C_SYSC_preadv fs/read_write.c:1209 [inline]
 compat_SyS_preadv+0x3b/0x50 fs/read_write.c:1203
 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
 do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
RIP: 0023:0xf7f35c79
RSP: 002b:00000000f773108c EFLAGS: 00000296 ORIG_RAX: 000000000000014d
RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000020b5c000
RDX: 0000000000000001 RSI: 000000000000000c RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
BUG: sleeping function called from invalid context at lib/usercopy.c:25
in_atomic(): 1, irqs_disabled(): 0, pid: 4677, name: syz-executor7
INFO: lockdep is turned off.
CPU: 0 PID: 4677 Comm: syz-executor7 Not tainted 4.15.0-rc7+ #167
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:4526
 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25
 copy_to_user include/linux/uaccess.h:155 [inline]
 seq_read+0x875/0x13d0 fs/seq_file.c:212
 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
 compat_readv+0x1bf/0x270 fs/read_write.c:1140
 do_compat_preadv64+0xd6/0x100 fs/read_write.c:1189
 C_SYSC_preadv fs/read_write.c:1209 [inline]
 compat_SyS_preadv+0x3b/0x50 fs/read_write.c:1203
 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
 do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
RIP: 0023:0xf7f35c79
RSP: 002b:00000000f773108c EFLAGS: 00000296 ORIG_RAX: 000000000000014d
RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000020b5c000
RDX: 0000000000000001 RSI: 000000000000000c RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
WARNING: CPU: 0 PID: 4677 at lib/usercopy.c:26 _copy_to_user+0xb5/0xc0 lib/usercopy.c:26