BTRFS warning (device <unknown>): duplicate device /dev/loop5 devid 1 generation 7 scanned by syz-executor.5 (10396)
BTRFS warning (device <unknown>): duplicate device /dev/loop5 devid 1 generation 7 scanned by systemd-udevd (8512)
------------[ cut here ]------------
WARNING: CPU: 0 PID: 13481 at fs/btrfs/volumes.c:1086 close_fs_devices.part.0.cold+0x11/0x30 fs/btrfs/volumes.c:1086
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 13481 Comm: syz-executor.2 Not tainted 4.19.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
caif:caif_disconnect_client(): nothing to disconnect
 panic+0x26a/0x50e kernel/panic.c:186
 __warn.cold+0x20/0x5a kernel/panic.c:541
 report_bug+0x262/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x1d7/0x310 arch/x86/kernel/traps.c:296
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:close_fs_devices.part.0.cold+0x11/0x30 fs/btrfs/volumes.c:1086
Code: c7 c7 e0 0f a5 88 e8 b8 fa f8 ff 0f 0b 49 c7 c4 ea ff ff ff e9 2f 3c f7 fa e8 c0 12 69 f9 48 c7 c7 e0 0f a5 88 e8 99 fa f8 ff <0f> 0b e9 0c 44 f7 fa e8 a8 12 69 f9 48 c7 c7 e0 0f a5 88 e8 81 fa
RSP: 0018:ffff88809c6b7b68 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814ddd51 RDI: ffffed10138d6f5f
RBP: ffff8880982d7000 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8880a99f1d80 R14: ffff8880b4fe44e0 R15: ffff8880a9c70d80
 close_fs_devices fs/btrfs/volumes.c:1113 [inline]
 btrfs_close_devices+0x95/0x1f0 fs/btrfs/volumes.c:1099
 close_ctree+0x3c8/0x850 fs/btrfs/disk-io.c:4047
 generic_shutdown_super+0x144/0x370 fs/super.c:456
 kill_anon_super+0x36/0x60 fs/super.c:1032
 btrfs_kill_super+0x49/0x550 fs/btrfs/super.c:2221
 deactivate_locked_super+0x94/0x160 fs/super.c:329
 deactivate_super+0x174/0x1a0 fs/super.c:360
 cleanup_mnt+0x1a8/0x290 fs/namespace.c:1098
 task_work_run+0x148/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4678b7
Code: ff d0 48 89 c7 b8 3c 00 00 00 0f 05 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef6336238 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000004678b7
RDX: 00007ffef633630c RSI: 0000000000000002 RDI: 00007ffef6336300
RBP: 00007ffef6336300 R08: 00000000ffffffff R09: 00007ffef63360d0
R10: 0000000002b2f8e3 R11: 0000000000000246 R12: 00000000004bebb2
R13: 00007ffef63373d0 R14: 0000000002b2f810 R15: 00007ffef6337410
Kernel Offset: disabled
Rebooting in 86400 seconds..