[syzbot] [bcachefs?] kernel BUG in bch2_btree_path_level_init (4)

[syzbot <syzbot+55c84106264e92ea9ada@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d69eb204c255 Merge tag 'net-6.17-rc5' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16d01962580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bd9738e00c1bbfb4
dashboard link: https://syzkaller.appspot.com/bug?extid=55c84106264e92ea9ada
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1788c962580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b0887c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/efa41ea44c52/disk-d69eb204.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d9ae66f326a4/vmlinux-d69eb204.xz
kernel image: https://storage.googleapis.com/syzbot-assets/967c2253578b/bzImage-d69eb204.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/9e7c59fc7ab3/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+55c84106264e92ea9ada@syzkaller.appspotmail.com

  running recovery passes: check_allocations,check_extents_to_backpointers,check_inodes
bcachefs (loop0): invalid bkey in btree_node btree=inodes level=0: u64s 18 type inode_v3 0:4102:U32_MAX len 0 ver 0: (unpack error)
  invalid variable length fields, deleting
bcachefs (loop0): accounting_read... done
bcachefs (loop0): alloc_read... done
bcachefs (loop0): alloc_read... done
bcachefs (loop0): snapshots_read... done
bcachefs (loop0): check_allocations...
------------[ cut here ]------------
kernel BUG at fs/bcachefs/btree_iter.c:633!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6000 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:bch2_btree_path_level_init+0xa01/0xa20 fs/bcachefs/btree_iter.c:633
Code: fd 90 0f 0b e8 90 05 a2 fd 90 0f 0b e8 88 05 a2 fd 90 0f 0b e8 80 05 a2 fd 90 0f 0b e8 78 05 a2 fd 90 0f 0b e8 70 05 a2 fd 90 <0f> 0b e8 68 05 a2 fd 90 0f 0b e8 60 05 a2 fd 90 0f 0b 66 66 66 66
RSP: 0018:ffffc90003f8e4a0 EFLAGS: 00010293
RAX: ffffffff841c59a0 RBX: ffff88803d33c2d8 RCX: ffff888030d73b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1007c6c817 R12: 0000000000000052
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  000055557a974500(0000) GS:ffff8881268c1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff395c5f24 CR3: 0000000027dc0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 btree_path_down fs/bcachefs/btree_iter.c:994 [inline]
 bch2_btree_path_traverse_one+0x1367/0x21d0 fs/bcachefs/btree_iter.c:1202
 bch2_btree_path_traverse fs/bcachefs/btree_iter.h:250 [inline]
 __bch2_btree_iter_peek fs/bcachefs/btree_iter.c:2267 [inline]
 bch2_btree_iter_peek_max+0x9e8/0x58f0 fs/bcachefs/btree_iter.c:2384
 bch2_btree_iter_peek_max_type fs/bcachefs/btree_iter.h:743 [inline]
 bch2_gc_btree fs/bcachefs/btree_gc.c:729 [inline]
 bch2_gc_btrees fs/bcachefs/btree_gc.c:792 [inline]
 bch2_check_allocations+0x120d/0x57b0 fs/bcachefs/btree_gc.c:1094
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x3bd/0x1060 fs/bcachefs/recovery_passes.c:539
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:610
 bch2_fs_recovery+0x2690/0x3a50 fs/bcachefs/recovery.c:1016
 bch2_fs_start+0xaaf/0xda0 fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0xb39/0x1520 fs/bcachefs/fs.c:2488
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcb57f3038a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007ffc365dc0a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc365dc130 RCX: 00007fcb57f3038a
RDX: 0000200000000040 RSI: 0000200000004940 RDI: 00007ffc365dc0f0
RBP: 0000200000000040 R08: 00007ffc365dc130 R09: 0000000000004000
R10: 0000000000004000 R11: 0000000000000246 R12: 0000200000004940
R13: 00007ffc365dc0f0 R14: 00000000000049ae R15: 0000200000000180
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_btree_path_level_init+0xa01/0xa20 fs/bcachefs/btree_iter.c:633
Code: fd 90 0f 0b e8 90 05 a2 fd 90 0f 0b e8 88 05 a2 fd 90 0f 0b e8 80 05 a2 fd 90 0f 0b e8 78 05 a2 fd 90 0f 0b e8 70 05 a2 fd 90 <0f> 0b e8 68 05 a2 fd 90 0f 0b e8 60 05 a2 fd 90 0f 0b 66 66 66 66
RSP: 0018:ffffc90003f8e4a0 EFLAGS: 00010293
RAX: ffffffff841c59a0 RBX: ffff88803d33c2d8 RCX: ffff888030d73b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1007c6c817 R12: 0000000000000052
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  000055557a974500(0000) GS:ffff8881268c1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff395c5f24 CR3: 0000000027dc0000 CR4: 00000000003526f0


---
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