------------[ cut here ]------------
WARNING: CPU: 1 PID: 10571 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: 10571 Comm: syz-executor.5 Not tainted 4.14.261-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:183
 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:ffff8880ab4df618 EFLAGS: 00010246
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc900078a0000
RDX: 0000000000040000 RSI: ffffffff82a70428 RDI: ffff888092c085e0
RBP: ffff8880b2aa9240 R08: 0000000000000286 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dead000000000200
R13: dead000000000100 R14: ffff8880903bb880 R15: ffff8880b2aa92e0
 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
======================================================
WARNING: the mand mount option is being deprecated and
         will be removed in v5.15!
======================================================
 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:2572 [inline]
 do_mount+0xe65/0x2a10 fs/namespace.c:2902
 SYSC_mount fs/namespace.c:3118 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3095
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f1582d6a3ca
RSP: 002b:00007f15816ddf88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00000000200009c0 RCX: 00007f1582d6a3ca
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f15816ddfe0
RBP: 00007f15816de020 R08: 00007f15816de020 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f15816ddfe0 R15: 0000000020000400
Kernel Offset: disabled
Rebooting in 86400 seconds..