assertion failed: !cache->nr_nodes, in fs/btrfs/backref.c:3160 (cache->nr_nodes=2)
------------[ cut here ]------------
kernel BUG at fs/btrfs/backref.c:3160!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 16286 Comm: syz.0.958 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:btrfs_backref_release_cache+0x1fe/0x230 fs/btrfs/backref.c:3160
Code: 0f 0b e8 e5 e8 c1 fd 48 c7 c7 e0 1a 78 8b 48 c7 c6 40 1b 78 8b 48 c7 c2 60 12 78 8b b9 58 0c 00 00 41 89 e8 e8 53 7f 24 fd 90 <0f> 0b e8 bb e8 c1 fd 48 c7 c7 80 1b 78 8b 48 c7 c6 e0 1b 78 8b 48
RSP: 0018:ffffc900040c77e8 EFLAGS: 00010246
RAX: 0000000000000052 RBX: ffff88805ee82020 RCX: 06a88d129ec25900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000818ead R12: dffffc0000000000
R13: 1ffff1100bdd0404 R14: ffff88805ee820f0 R15: ffff88805e7c1a08
FS:  00007fb36bea66c0(0000) GS:ffff88812637d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff8e3fb0000 CR3: 000000005b4a0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 relocate_block_group+0xb84/0xe90 fs/btrfs/relocation.c:3690
 do_nonremap_reloc+0xa7/0x560 fs/btrfs/relocation.c:5323
 btrfs_relocate_block_group+0x6e2/0xaf0 fs/btrfs/relocation.c:5490
 btrfs_relocate_chunk+0x114/0x830 fs/btrfs/volumes.c:3647
 __btrfs_balance+0x1b6e/0x29e0 fs/btrfs/volumes.c:4586
 btrfs_balance+0xaa6/0x1180 fs/btrfs/volumes.c:4973
 btrfs_ioctl_balance+0x3dd/0x640 fs/btrfs/ioctl.c:3474
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/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: 0033:0x7fb36dc4ce59
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:00007fb36bea6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb36dec5fa0 RCX: 00007fb36dc4ce59
RDX: 0000200000000180 RSI: 00000000c4009420 RDI: 0000000000000004
RBP: 00007fb36dce2d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb36dec6038 R14: 00007fb36dec5fa0 R15: 00007fff983043c8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btrfs_backref_release_cache+0x1fe/0x230 fs/btrfs/backref.c:3160
Code: 0f 0b e8 e5 e8 c1 fd 48 c7 c7 e0 1a 78 8b 48 c7 c6 40 1b 78 8b 48 c7 c2 60 12 78 8b b9 58 0c 00 00 41 89 e8 e8 53 7f 24 fd 90 <0f> 0b e8 bb e8 c1 fd 48 c7 c7 80 1b 78 8b 48 c7 c6 e0 1b 78 8b 48
RSP: 0018:ffffc900040c77e8 EFLAGS: 00010246
RAX: 0000000000000052 RBX: ffff88805ee82020 RCX: 06a88d129ec25900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000818ead R12: dffffc0000000000
R13: 1ffff1100bdd0404 R14: ffff88805ee820f0 R15: ffff88805e7c1a08
FS:  00007fb36bea66c0(0000) GS:ffff88812637d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff8e3d32e9c CR3: 000000005b4a0000 CR4: 00000000003526f0