base_sock_release(00000000eaa4647b) sk=          (null)
=====================================
WARNING: bad unlock balance detected!
4.19.209-syzkaller #0 Not tainted
-------------------------------------
kworker/u4:5/9512 is trying to release lock (&file->mut) at:
base_sock_release(0000000065154963) sk=000000008b63842d
[<ffffffff85f5c1b5>] ucma_event_handler+0x745/0xf50 drivers/infiniband/core/ucma.c:396
but there are no more locks to release!

other info that might help us debug this:
4 locks held by kworker/u4:5/9512:
 #0: 000000004d04511e ((wq_completion)"ib_addr"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124
 #1: 000000009c4521e8 ((work_completion)(&(&req->work)->work)){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128
 #2: 00000000304f4fc4 (&id_priv->handler_mutex){+.+.}, at: addr_handler+0xaf/0x5f0 drivers/infiniband/core/cma.c:2887
 #3: 0000000099ce1e14 (&file->mut){+.+.}, at: ucma_event_handler+0xb2/0xf50 drivers/infiniband/core/ucma.c:356

stack backtrace:
CPU: 1 PID: 9512 Comm: kworker/u4:5 Not tainted 4.19.209-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ib_addr process_one_req
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 print_unlock_imbalance_bug kernel/locking/lockdep.c:149 [inline]
 __lock_release kernel/locking/lockdep.c:3679 [inline]
 lock_release.cold+0xe/0x4a kernel/locking/lockdep.c:3927
 __mutex_unlock_slowpath+0x89/0x610 kernel/locking/mutex.c:1203
 ucma_event_handler+0x745/0xf50 drivers/infiniband/core/ucma.c:396
 addr_handler+0x2c1/0x5f0 drivers/infiniband/core/cma.c:2920
 process_one_req+0xf1/0x620 drivers/infiniband/core/addr.c:569
 process_one_work+0x864/0x1570 kernel/workqueue.c:2153
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
netlink: 40 bytes leftover after parsing attributes in process `syz-executor.1'.
base_sock_release(00000000c6006d88) sk=00000000def8c9ff
base_sock_release(00000000d7d7cd77) sk=0000000078b4aa77
netlink: 40 bytes leftover after parsing attributes in process `syz-executor.1'.