------------[ cut here ]------------
WARNING: CPU: 1 PID: 8537 at fs/btrfs/volumes.c:1174 close_fs_devices+0x71d/0x930 fs/btrfs/volumes.c:1174
Modules linked in:
CPU: 1 PID: 8537 Comm: syz-executor956 Not tainted 5.10.0-rc5-next-20201127-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:1174
Code: e8 88 2f 42 fe 85 db 0f 85 5d f9 ff ff e8 9b 27 42 fe 0f 0b e9 51 f9 ff ff e8 8f 27 42 fe 0f 0b e9 c0 fe ff ff e8 83 27 42 fe <0f> 0b e9 f9 fe ff ff 48 c7 c7 1c 80 ee 8c e8 40 fb 84 fe e9 11 f9
RSP: 0018:ffffc9000183f750 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88801e07b580 RSI: ffffffff832e99dd RDI: 0000000000000003
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffff88801a17b93b
R10: ffffffff832e98d4 R11: 0000000000000000 R12: ffff88801a17b938
R13: ffff88801a17b9f4 R14: ffff888013e1c908 R15: ffff88801a17b850
FS:  00000000025a7880(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f674003e048 CR3: 0000000012337000 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:1186
 open_ctree+0x3f90/0x4035 fs/btrfs/disk-io.c:3484
 btrfs_fill_super fs/btrfs/super.c:1362 [inline]
 btrfs_mount_root.cold+0x14/0x165 fs/btrfs/super.c:1731
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 fc_mount fs/namespace.c:983 [inline]
 vfs_kern_mount.part.0+0xd3/0x170 fs/namespace.c:1013
 vfs_kern_mount+0x3c/0x60 fs/namespace.c:1000
 btrfs_mount+0x234/0xa20 fs/btrfs/super.c:1791
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 do_new_mount fs/namespace.c:2896 [inline]
 path_mount+0x12ae/0x1e70 fs/namespace.c:3227
 do_mount fs/namespace.c:3240 [inline]
 __do_sys_mount fs/namespace.c:3448 [inline]
 __se_sys_mount fs/namespace.c:3425 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3425
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4492fa
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 cd a2 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 aa a2 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffe66329388 EFLAGS: 00000293 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004492fa
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe663293d0
RBP: 00007ffe66329410 R08: 00007ffe66329410 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 00007ffe663293d0 R14: 0000000000000003 R15: 0000000000000005