loop0: detected capacity change from 0 to 32768
BTRFS: device fsid 395ef67a-297e-477c-816d-cd80a5b93e5d devid 1 transid 8 /dev/loop0 (7:0) scanned by syz.0.0 (5317)
BTRFS info (device loop0): first mount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d
BTRFS info (device loop0): using sha256 checksum algorithm
BTRFS info (device loop0): enabling ssd optimizations
BTRFS info (device loop0): turning on async discard
BTRFS info (device loop0): enabling free space tree
sysfs: cannot create duplicate filename '/fs/btrfs/395ef67a-297e-477c-816d-cd80a5b93e5d/devices/nullb0'
CPU: 0 UID: 0 PID: 5317 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 sysfs_warn_dup+0x8e/0xa0 fs/sysfs/dir.c:30
 sysfs_do_create_link_sd+0xc0/0x110 fs/sysfs/symlink.c:51
 btrfs_sysfs_add_device+0x13f/0x650 fs/btrfs/sysfs.c:2155
 btrfs_init_new_device+0xdb8/0x19e0 fs/btrfs/volumes.c:2996
 btrfs_ioctl_add_dev+0x1ad/0x640 fs/btrfs/ioctl.c:2558
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc9f6b9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc9f7ae2fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc9f6e26090 RCX: 00007fc9f6b9e0d9
RDX: 0000200000001000 RSI: 000000005000940a RDI: 0000000000000004
RBP: 00007fc9f6c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc9f6e26128 R14: 00007fc9f6e26090 R15: 00007fffe86c22a8
 </TASK>
BTRFS warning (device loop0): creating sysfs device link for devid 2 failed: -17
------------[ cut here ]------------
btrfs_abort_should_print_stack(__error)
WARNING: fs/btrfs/volumes.c:3013 at btrfs_init_new_device+0x1913/0x19e0 fs/btrfs/volumes.c:3013, CPU#0: syz.0.0/5317
Modules linked in:
CPU: 0 UID: 0 PID: 5317 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:btrfs_init_new_device+0x1913/0x19e0 fs/btrfs/volumes.c:3013
Code: 00 00 41 83 fe f4 0f 85 d8 00 00 00 e8 66 c8 aa fd e9 d7 00 00 00 e8 5c c8 aa fd eb 10 e8 55 c8 aa fd eb 09 e8 4e c8 aa fd 90 <0f> 0b 90 44 89 f1 f7 d9 e9 7b fc ff ff 89 d9 80 e1 07 38 c1 0f 8c
RSP: 0018:ffffc9000e267da8 EFLAGS: 00010293
RAX: ffffffff841c4a92 RBX: ffff888051f58001 RCX: ffff88801aea2540
RDX: 0000000000000000 RSI: ffffffff8f1d9940 RDI: 00000000ffffffef
RBP: dffffc0000000000 R08: ffff88801aea2540 R09: 0000000000000003
R10: 00000000fffffffb R11: 0000000000000000 R12: ffff888051f58968
R13: 0000000000000002 R14: 00000000ffffffef R15: ffff888051f58000
FS:  00007fc9f7ae36c0(0000) GS:ffff88808c549000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000405a5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 btrfs_ioctl_add_dev+0x1ad/0x640 fs/btrfs/ioctl.c:2558
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc9f6b9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc9f7ae2fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc9f6e26090 RCX: 00007fc9f6b9e0d9
RDX: 0000200000001000 RSI: 000000005000940a RDI: 0000000000000004
RBP: 00007fc9f6c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc9f6e26128 R14: 00007fc9f6e26090 R15: 00007fffe86c22a8
 </TASK>