------------[ cut here ]------------
WARNING: CPU: 1 PID: 5542 at fs/btrfs/volumes.c:936 __btrfs_close_devices+0x888/0xb20 fs/btrfs/volumes.c:936
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 5542 Comm: syz-executor.2 Not tainted 4.14.232-syzkaller #0
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+0x1b2/0x281 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x20/0x44 kernel/panic.c:547
 report_bug+0x208/0x250 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:__btrfs_close_devices+0x888/0xb20 fs/btrfs/volumes.c:936
RSP: 0018:ffff88803bcf7618 EFLAGS: 00010246
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90009908000
RDX: 0000000000040000 RSI: ffffffff82a6c338 RDI: ffff8880aa3e4a20
RBP: ffff8880abb07b00 R08: 0000000000000286 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dead000000000200
R13: dead000000000100 R14: ffff8880b1d7a700 R15: ffff8880abb07ba0
 btrfs_close_devices+0x24/0x140 fs/btrfs/volumes.c:949
 open_ctree+0x241/0x7400 fs/btrfs/disk-io.c:3101
 btrfs_fill_super fs/btrfs/super.c:1147 [inline]
 btrfs_mount+0x1915/0x1fe0 fs/btrfs/super.c:1631
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount+0x3c/0x60 fs/namespace.c:1036
 mount_subvol fs/btrfs/super.c:1398 [inline]
 btrfs_mount+0x42a/0x1fe0 fs/btrfs/super.c:1569
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x467b1a
RSP: 002b:00007ff276f9cfa8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 0000000000467b1a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ff276f9d000
RBP: 00007ff276f9d040 R08: 00007ff276f9d040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 00007ff276f9d000 R15: 0000000020001240
Kernel Offset: disabled
Rebooting in 86400 seconds..