------------[ cut here ]------------
WARNING: CPU: 1 PID: 8482 at fs/btrfs/volumes.c:1172 close_fs_devices+0x71d/0x930 fs/btrfs/volumes.c:1172
Modules linked in:
CPU: 1 PID: 8482 Comm: syz-executor.0 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:close_fs_devices+0x71d/0x930 fs/btrfs/volumes.c:1172
Code: e8 e8 d5 41 fe 85 db 0f 85 5d f9 ff ff e8 5b ce 41 fe 0f 0b e9 51 f9 ff ff e8 4f ce 41 fe 0f 0b e9 c0 fe ff ff e8 43 ce 41 fe <0f> 0b e9 f9 fe ff ff 48 c7 c7 5c 89 ef 8c e8 e0 61 84 fe e9 11 f9
RSP: 0018:ffffc900016afbe8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff888020273780 RSI: ffffffff8330a74d RDI: 0000000000000003
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffff88801833493b
R10: ffffffff8330a644 R11: 0000000000000000 R12: ffff888018334938
R13: ffff8880183349f4 R14: ffff88802fe8d908 R15: ffff888018334850
FS:  000000000209c940(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000778000 CR3: 000000005c073000 CR4: 0000000000350ef0
Call Trace:
 btrfs_close_devices+0x8e/0x4b0 fs/btrfs/volumes.c:1184
 close_ctree+0x694/0x6d7 fs/btrfs/disk-io.c:4205
 generic_shutdown_super+0x144/0x370 fs/super.c:464
 kill_anon_super+0x36/0x60 fs/super.c:1055
 btrfs_kill_super+0x38/0x50 fs/btrfs/super.c:2313
 deactivate_locked_super+0x94/0x160 fs/super.c:335
 deactivate_super+0xad/0xd0 fs/super.c:366
 cleanup_mnt+0x3a3/0x530 fs/namespace.c:1118
 task_work_run+0xdd/0x190 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x460c47
Code: 64 89 04 25 d0 02 00 00 58 5f ff d0 48 89 c7 e8 2f be ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe44fa6368 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460c47
RDX: 00000000004033a8 RSI: 0000000000000002 RDI: 00007ffe44fa6410
RBP: 0000000000225b1a R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffe44fa74c0
R13: 000000000209da60 R14: 0000000000000000 R15: 00000000002257ae