=====================================
WARNING: bad unlock balance detected!
4.15.0-rc3+ #128 Not tainted
-------------------------------------
syzkaller971460/3195 is trying to release lock (mrt_lock) at:
[<000000006898068d>] 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 syzkaller971460/3195:
 #0:  (&p->lock){+.+.}, at: [<00000000744a6565>] seq_read+0xd5/0x13d0 fs/seq_file.c:165

stack backtrace:
CPU: 1 PID: 3195 Comm: syzkaller971460 Not tainted 4.15.0-rc3+ #128
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:3561
 __lock_release kernel/locking/lockdep.c:3775 [inline]
 lock_release+0x5f9/0xda0 kernel/locking/lockdep.c:4023
 __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 _raw_read_unlock+0x1a/0x30 kernel/locking/spinlock.c:255
 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+0x3db/0x5b0 fs/read_write.c:897
 compat_readv+0x1bf/0x270 fs/read_write.c:1140
 do_compat_preadv64+0xdc/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+0x51/0x60 arch/x86/entry/entry_64_compat.S:125
RIP: 0023:0xf7f73c79
RSP: 002b:00000000e574a15c EFLAGS: 00000292 ORIG_RAX: 000000000000014d
RAX: ffffffffffffffda RBX: 000000000000000f RCX: 0000000020a3afb0
RDX: 0000000000000001 RSI: 0000000000000067 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: 3195, name: syzkaller971460
INFO: lockdep is turned off.
CPU: 1 PID: 3195 Comm: syzkaller971460 Not tainted 4.15.0-rc3+ #128
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:4525
 _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+0x3db/0x5b0 fs/read_write.c:897
 compat_readv+0x1bf/0x270 fs/read_write.c:1140
 do_compat_preadv64+0xdc/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+0x51/0x60 arch/x86/entry/entry_64_compat.S:125
RIP: 0023:0xf7f73c79
RSP: 002b:00000000e574a15c EFLAGS: 00000292 ORIG_RAX: 000000000000014d
RAX: ffffffffffffffda RBX: 000000000000000f RCX: 0000000020a3afb0
RDX: 0000000000000001 RSI: 0000000000000067 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
WARNING: CPU: 1 PID: 3195 at lib/usercopy.c:26 _copy_to_user+0xb5/0xc0 lib/usercopy.c:26