------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(depth <= 0)
WARNING: CPU: 0 PID: 30691 at kernel/locking/lockdep.c:3766 __lock_release kernel/locking/lockdep.c:3766 [inline]
WARNING: CPU: 0 PID: 30691 at kernel/locking/lockdep.c:3766 lock_release+0x5de/0xda0 kernel/locking/lockdep.c:4023
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 30691 Comm: syz-executor0 Not tainted 4.15.0-rc2+ #125
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
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x211/0x2d0 lib/bug.c:184
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
 fixup_bug arch/x86/kernel/traps.c:246 [inline]
 do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:930
RIP: 0010:__lock_release kernel/locking/lockdep.c:3766 [inline]
RIP: 0010:lock_release+0x5de/0xda0 kernel/locking/lockdep.c:4023
RSP: 0018:ffff880192b7f558 EFLAGS: 00010082
RAX: dffffc0000000008 RBX: 1ffff1003256feb0 RCX: ffffffff815a047e
RDX: 0000000000010000 RSI: ffffc900037c4000 RDI: 0000000000000000
RBP: ffff880192b7f6c8 R08: 0000000000000001 R09: 0000000000000000
R10: ffff8801d7e884c0 R11: fffffbfff0e89463 R12: ffff880192b7f5a0
R13: ffff880192b7f6a0 R14: ffff8801cf1ce418 R15: ffffffff8748ad20
 up_write+0x6b/0x120 kernel/locking/rwsem.c:131
 destroy_unused_super.part.7+0x18/0xd0 fs/super.c:163
 destroy_unused_super fs/super.c:505 [inline]
 alloc_super fs/super.c:258 [inline]
 sget_userns+0x905/0xe20 fs/super.c:503
 mount_pseudo_xattr+0x12c/0x560 fs/libfs.c:249
 mount_pseudo include/linux/fs.h:2156 [inline]
 pipefs_mount+0x32/0x40 fs/pipe.c:1188
 mount_fs+0x66/0x2d0 fs/super.c:1219
 vfs_kern_mount.part.26+0xc6/0x4a0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:2509 [inline]
 do_new_mount fs/namespace.c:2512 [inline]
 do_mount+0xea4/0x2bb0 fs/namespace.c:2841
 C_SYSC_mount fs/compat.c:195 [inline]
 compat_SyS_mount+0xd0/0x1070 fs/compat.c:160
 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: 0023:0xf7ff9c79
RSP: 002b:00000000f77f508c EFLAGS: 00000296 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 000000002088aff8 RCX: 0000000020026ff8
RDX: 00000000202e6000 RSI: 0000000000000000 RDI: 000000002000a000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..