------------[ cut here ]------------
WARNING: CPU: 1 PID: 6921 at fs/btrfs/volumes.c:1172 close_fs_devices+0x715/0x930 fs/btrfs/volumes.c:1172
Modules linked in:
CPU: 1 PID: 6921 Comm: syz-executor.5 Not tainted 5.9.0-rc5-next-20200915-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:close_fs_devices+0x715/0x930 fs/btrfs/volumes.c:1172
Code: e8 d0 3f 6c fe 85 db 0f 85 65 f9 ff ff e8 43 43 6c fe 0f 0b e9 59 f9 ff ff e8 37 43 6c fe 0f 0b e9 c0 fe ff ff e8 2b 43 6c fe <0f> 0b e9 f9 fe ff ff 48 c7 c7 bc 21 e6 8a e8 38 c0 ac fe e9 19 f9
RSP: 0018:ffffc90005727be0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: ffffffff8306873c
RDX: ffff88805ab74280 RSI: ffffffff83068845 RDI: 0000000000000007
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffff888097254933
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888097254930
R13: ffff8880972549ec R14: ffff8880a0858d08 R15: ffff888097254850
FS:  0000000001d4b940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f67e26b2db8 CR3: 000000005ab3d000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 btrfs_close_devices+0x8e/0x4b0 fs/btrfs/volumes.c:1184
 close_ctree+0x694/0x6d7 fs/btrfs/disk-io.c:4149
 generic_shutdown_super+0x144/0x370 fs/super.c:464
 kill_anon_super+0x36/0x60 fs/super.c:1108
 btrfs_kill_super+0x38/0x50 fs/btrfs/super.c:2263
 deactivate_locked_super+0x94/0x160 fs/super.c:335
 deactivate_super+0xad/0xd0 fs/super.c:366
 cleanup_mnt+0x399/0x500 fs/namespace.c:1123
 task_work_run+0xdd/0x190 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190
 syscall_exit_to_user_mode+0x7a/0x2c0 kernel/entry/common.c:265
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x460027
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 fd 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd77d628b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460027
RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffd77d62960
RBP: 00000000000005fe R08: 0000000000000000 R09: 000000000000000b
R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffd77d639f0
R13: 0000000001d4ca60 R14: 0000000000000000 R15: 00007ffd77d639f0