syzbot

=====================================
WARNING: bad unlock balance detected!
4.14.292-syzkaller #0 Not tainted
-------------------------------------
syz-executor956/8126 is trying to release lock (&file->mut) at:
[<ffffffff855217fb>] ucma_destroy_id+0x1eb/0x420 drivers/infiniband/core/ucma.c:606
but there are no more locks to release!

other info that might help us debug this:
1 lock held by syz-executor956/8126:
 #0:  (&file->mut){+.+.}, at: [<ffffffff8552179c>] ucma_destroy_id+0x18c/0x420 drivers/infiniband/core/ucma.c:604

stack backtrace:
CPU: 1 PID: 8126 Comm: syz-executor956 Not tainted 4.14.292-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_unlock_imbalance_bug include/trace/events/lock.h:58 [inline]
 __lock_release kernel/locking/lockdep.c:3769 [inline]
 lock_release.cold+0x70/0xbf kernel/locking/lockdep.c:4017
 __mutex_unlock_slowpath+0x75/0x770 kernel/locking/mutex.c:1018
 ucma_destroy_id+0x1eb/0x420 drivers/infiniband/core/ucma.c:606
 ucma_write+0x206/0x2c0 drivers/infiniband/core/ucma.c:1672
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f45d87c9a69
RSP: 002b:00007f45d875a308 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f45d8851418 RCX: 00007f45d87c9a69
RDX: 0000000000000018 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00007f45d8851410 R08: 00007f45d875a700 R09: 0000000000000000
R10: 00007f45d875a700 R11: 0000000000000246 R12: 00007f45d885141c
R13: 00007f45d881f074 R14: 006d635f616d6472 R15: 0000000000022000