IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
=====================================
[ BUG: bad unlock balance detected! ]
4.2.0-rc8+ #1 Not tainted
-------------------------------------
syz-executor4/6152 is trying to release lock (&file->mut) at:
[<ffffffff8224e0c9>] mutex_unlock+0x9/0x10 kernel/locking/mutex.c:437
but there are no more locks to release!

other info that might help us debug this:
1 lock held by syz-executor4/6152:
 #0:  (&file->mut){+.+.+.}, at: [<ffffffff81c863f9>] ucma_destroy_id+0xf9/0x1d0 drivers/infiniband/core/ucma.c:589

stack backtrace:
CPU: 0 PID: 6152 Comm: syz-executor4 Not tainted 4.2.0-rc8+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffffffff8224e0c9 ffff8800b7857c88 ffffffff82244b96 0000000000000011
 ffff880213efe7c0 ffff8800b7857cb8 ffffffff811b2c60 0000000000000006
 ffff88020f847c60 ffffffff8224e0c9 ffff880213efef38 ffff8800b7857d58
Call Trace:
 [<ffffffff82244b96>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff82244b96>] dump_stack+0x4c/0x65 lib/dump_stack.c:50
 [<ffffffff811b2c60>] print_unlock_imbalance_bug+0xe0/0xf0 kernel/locking/lockdep.c:3259
 [<ffffffff811b7bac>] __lock_release kernel/locking/lockdep.c:3383 [inline]
 [<ffffffff811b7bac>] lock_release+0x36c/0x550 kernel/locking/lockdep.c:3604
 [<ffffffff8224df74>] __mutex_unlock_common_slowpath kernel/locking/mutex.c:735 [inline]
 [<ffffffff8224df74>] __mutex_unlock_slowpath+0x94/0x1e0 kernel/locking/mutex.c:760
 [<ffffffff8224e0c9>] mutex_unlock+0x9/0x10 kernel/locking/mutex.c:437
 [<ffffffff81c8640c>] ucma_destroy_id+0x10c/0x1d0 drivers/infiniband/core/ucma.c:591
 [<ffffffff81c85329>] ucma_write+0x79/0xb0 drivers/infiniband/core/ucma.c:1591
 [<ffffffff812dab83>] __vfs_write+0x23/0xe0 fs/read_write.c:489
 [<ffffffff812db251>] vfs_write+0xa1/0x1a0 fs/read_write.c:538
 [<ffffffff812dbe74>] SYSC_write fs/read_write.c:585 [inline]
 [<ffffffff812dbe74>] SyS_write+0x44/0xa0 fs/read_write.c:577
 [<ffffffff822519f2>] entry_SYSCALL_64_fastpath+0x16/0x7a
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6130 at lib/idr.c:505 idr_remove_warning lib/idr.c:505 [inline]()
WARNING: CPU: 0 PID: 6130 at lib/idr.c:505 idr_remove+0x154/0x240 lib/idr.c:559()
idr_remove called for id=5 which is not allocated.