loop0: detected capacity change from 0 to 32768
BTRFS: device fsid ed167579-eb65-4e76-9a50-61ac97e9b59d devid 1 transid 8 /dev/loop0 (7:0) scanned by syz.0.0 (5321)
BTRFS info (device loop0): first mount of filesystem ed167579-eb65-4e76-9a50-61ac97e9b59d
BTRFS info (device loop0): using sha256 (sha256-avx2) checksum algorithm
BTRFS info (device loop0): disk space caching is enabled
BTRFS warning (device loop0): space cache v1 is being deprecated and will be removed in a future release, please use -o space_cache=v2
BTRFS info (device loop0): rebuilding free space tree
BTRFS info (device loop0): disabling free space tree
BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1)
BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2)
BTRFS info (device loop0): balance: start -d -m
BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
BTRFS info (device loop0): relocating block group 5242880 flags data|metadata
assertion failed: !cache->nr_nodes, in fs/btrfs/backref.c:3160
------------[ cut here ]------------
kernel BUG at fs/btrfs/backref.c:3160!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5321 Comm: syz.0.0 Not tainted 6.14.0-syzkaller-10167-g93d52288679e #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:btrfs_backref_release_cache+0x1b5/0x1e0 fs/btrfs/backref.c:3160
Code: 1c fd 90 0f 0b e8 1b 00 b9 fd 48 c7 c7 20 22 8e 8c 48 c7 c6 c0 2a 8e 8c 48 c7 c2 c0 22 8e 8c b9 58 0c 00 00 e8 1c a1 1c fd 90 <0f> 0b e8 f4 ff b8 fd 48 c7 c7 20 22 8e 8c 48 c7 c6 00 2b 8e 8c 48
RSP: 0018:ffffc9000d447858 EFLAGS: 00010246
RAX: 000000000000003e RBX: 0000000000000002 RCX: f9cee352a1c2d200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000d447a20 R08: ffffffff81a29c5c R09: 1ffff92001a88ea8
R10: dffffc0000000000 R11: fffff52001a88ea9 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88805221b0f0 R15: ffff88805221b020
FS:  00007f6bafd1a6c0(0000) GS:ffff88808c5b7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 0000000033044000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 relocate_block_group+0xac4/0xd50 fs/btrfs/relocation.c:3665
 btrfs_relocate_block_group+0x777/0xd80 fs/btrfs/relocation.c:4011
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3511
 __btrfs_balance+0x1a93/0x25e0 fs/btrfs/volumes.c:4292
 btrfs_balance+0xbde/0x10c0 fs/btrfs/volumes.c:4669
 btrfs_ioctl_balance+0x3f5/0x660 fs/btrfs/ioctl.c:3586
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6baef8d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6bafd1a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6baf1a5fa0 RCX: 00007f6baef8d169
RDX: 0000200000000180 RSI: 00000000c4009420 RDI: 0000000000000004
RBP: 00007f6baf00e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6baf1a5fa0 R15: 00007fff20f21e48
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btrfs_backref_release_cache+0x1b5/0x1e0 fs/btrfs/backref.c:3160
Code: 1c fd 90 0f 0b e8 1b 00 b9 fd 48 c7 c7 20 22 8e 8c 48 c7 c6 c0 2a 8e 8c 48 c7 c2 c0 22 8e 8c b9 58 0c 00 00 e8 1c a1 1c fd 90 <0f> 0b e8 f4 ff b8 fd 48 c7 c7 20 22 8e 8c 48 c7 c6 00 2b 8e 8c 48
RSP: 0018:ffffc9000d447858 EFLAGS: 00010246
RAX: 000000000000003e RBX: 0000000000000002 RCX: f9cee352a1c2d200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000d447a20 R08: ffffffff81a29c5c R09: 1ffff92001a88ea8
R10: dffffc0000000000 R11: fffff52001a88ea9 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88805221b0f0 R15: ffff88805221b020
FS:  00007f6bafd1a6c0(0000) GS:ffff88808c5b7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 0000000033044000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400