Message-Id: <2EF5EFCC-2F5A-4B86-9D12-92A7C6712DF3@gmail.com>
Date: Tue, 5 Aug 2025 11:52:14 +0800
From: Alan Huang <mmpgouride@...il.com>
To: syzbot <syzbot+210dfbddd64294066983@...kaller.appspotmail.com>
Cc: kent.overstreet@...ux.dev,
 linux-bcachefs@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] kernel BUG in bch2_trans_update_by_path

On Jun 19, 2025, at 19:18, syzbot <syzbot+210dfbddd64294066983@...kaller.appspotmail.com> wrote:
> 
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    fb4d33ab452e Merge tag '6.16-rc2-ksmbd-server-fixes' of gi..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12eb6d0c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d11f52d3049c3790
> dashboard link: https://syzkaller.appspot.com/bug?extid=210dfbddd64294066983
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-fb4d33ab.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/123054ec64c2/vmlinux-fb4d33ab.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/5e5e20b8a324/bzImage-fb4d33ab.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+210dfbddd64294066983@...kaller.appspotmail.com
> 
> bcachefs (loop0): no nodes found for btree extents, continuing
> bcachefs (loop0): btree root inodes unreadable, must recover from scan
> bcachefs (loop0): bch2_get_scanned_nodes(): recovery btree=inodes level=0 POS_MIN - SPOS_MAX
> bcachefs (loop0): bch2_get_scanned_nodes(): recovering u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 7589ab5e0c11cc7a written 24 min_key POS_MIN durability: 1 ptr: 0:38:0 gen 0
> bcachefs (loop0): empty interior btree node at btree=inodes level=1
>  u64s 5 type btree_ptr SPOS_MAX len 0 ver 0, fixing
> bcachefs (loop0): bch2_btree_repair_topology_recurse(): error ECHILD
> bcachefs (loop0): empty btree root inodes
> bcachefs (loop0): btree root subvolumes unreadable, must recover from scan
> bcachefs (loop0): bch2_get_scanned_nodes(): recovery btree=subvolumes level=0 POS_MIN - SPOS_MAX
> bcachefs (loop0): bch2_get_scanned_nodes(): recovering u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq c0bef60d07ceb940 written 16 min_key POS_MIN durability: 1 ptr: 0:35:0 gen 0
> done
> bcachefs (loop0): accounting_read... done
> bcachefs (loop0): alloc_read... done
> bcachefs (loop0): snapshots_read... done
> bcachefs (loop0): check_allocations...
> bcachefs (loop0): bucket 0:26 data type btree ptr gen 0 missing in alloc btree
>  while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq ac62141f8dc7e261 written 24 min_key POS_MIN durability: 1 ptr: 0:26:0 gen 0, fixing
> bcachefs (loop0): bucket 0:41 data type btree ptr gen 0 missing in alloc btree
>  while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 9aa2895aefce4bdf written 24 min_key POS_MIN durability: 1 ptr: 0:41:0 gen 0, fixing
> bcachefs (loop0): bucket 0:35 data type btree ptr gen 0 missing in alloc btree
>  while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq c0bef60d07ceb940 written 16 min_key POS_MIN durability: 1 ptr: 0:35:0 gen 0, fixing
> bcachefs (loop0): bucket 0:1 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:1 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:2 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:2 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:3 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:3 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:4 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:4 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:5 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:5 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:6 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:6 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:7 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:7 gen 0 data type sb has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:8 gen 0 has wrong data_type: got free, should be sb, fixing
> bcachefs (loop0): bucket 0:8 gen 0 data type sb has wrong dirty_sectors: got 0, should be 8, fixing
> bcachefs (loop0): bucket 0:9 gen 0 has wrong data_type: got free, should be journal, fixing
> bcachefs (loop0): bucket 0:9 gen 0 data type journal has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:10 gen 0 has wrong data_type: got free, should be journal, fixing
> bcachefs (loop0): bucket 0:10 gen 0 data type journal has wrong dirty_sectors: got 0, should be 256, fixing
> bcachefs (loop0): bucket 0:11 gen 0 has wrong data_type: got free, should be journal, fixing
>  Ratelimiting new instances of previous error
> bcachefs (loop0): bucket 0:11 gen 0 data type journal has wrong dirty_sectors: got 0, should be 256, fixing
>  Ratelimiting new instances of previous error
> done
> bcachefs (loop0): going read-write
> bcachefs (loop0): journal_replay...
> ------------[ cut here ]------------
> kernel BUG at fs/bcachefs/btree_update.c:375!
> Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
> CPU: 0 UID: 0 PID: 5324 Comm: syz.0.0 Not tainted 6.16.0-rc2-syzkaller-00082-gfb4d33ab452e #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:bch2_trans_update_by_path+0x1efb/0x1f30 fs/bcachefs/btree_update.c:375
> Code: 80 e1 07 fe c1 38 c1 0f 8c 40 f7 ff ff 48 8b 7c 24 28 e8 88 5e fa fd e9 31 f7 ff ff e8 ce df 96 fd 90 0f 0b e8 c6 df 96 fd 90 <0f> 0b e8 be df 96 fd 90 0f 0b e8 b6 df 96 fd 90 0f 0b e8 ae df 96
> RSP: 0018:ffffc9000d6be9c8 EFLAGS: 00010283
> RAX: ffffffff84297c8a RBX: 0000000000008541 RCX: 0000000000100000
> RDX: ffffc9000e002000 RSI: 00000000000b63ac RDI: 00000000000b63ad
> RBP: 1ffff1100a622002 R08: ffffffff844d525f R09: 0000000000000002
> R10: 0000000000000003 R11: 0000000000000002 R12: 1ffff1100a62205e
> R13: ffff888053110010 R14: 0000000000000088 R15: ffff8880531102f0
> FS:  00007f529748d6c0(0000) GS:ffff88808d251000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fffb9f0fabc CR3: 0000000043ca6000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> bch2_trans_update_ip+0x9a6/0x1db0 fs/bcachefs/btree_update.c:531
> bch2_trans_update fs/bcachefs/btree_update.h:123 [inline]
> bch2_journal_replay_key+0x46a/0xb10 fs/bcachefs/recovery.c:311
> bch2_journal_replay+0x1727/0x2620 fs/bcachefs/recovery.c:396
> bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
> __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
> bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
> bch2_fs_recovery+0x25fd/0x3950 fs/bcachefs/recovery.c:989
> bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1203
> bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
> vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
> do_new_mount+0x24a/0xa40 fs/namespace.c:3885
> do_mount fs/namespace.c:4222 [inline]
> __do_sys_mount fs/namespace.c:4433 [inline]
> __se_sys_mount+0x317/0x410 fs/namespace.c:4410
> 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: 0033:0x7f52965900ca
> 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:00007f529748ce68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007f529748cef0 RCX: 00007f52965900ca
> RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 00007f529748ceb0
> RBP: 00002000000000c0 R08: 00007f529748cef0 R09: 0000000000818001
> R10: 0000000000818001 R11: 0000000000000246 R12: 0000200000000080
> R13: 00007f529748ceb0 R14: 00000000000059a7 R15: 0000200000000200
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:bch2_trans_update_by_path+0x1efb/0x1f30 fs/bcachefs/btree_update.c:375
> Code: 80 e1 07 fe c1 38 c1 0f 8c 40 f7 ff ff 48 8b 7c 24 28 e8 88 5e fa fd e9 31 f7 ff ff e8 ce df 96 fd 90 0f 0b e8 c6 df 96 fd 90 <0f> 0b e8 be df 96 fd 90 0f 0b e8 b6 df 96 fd 90 0f 0b e8 ae df 96
> RSP: 0018:ffffc9000d6be9c8 EFLAGS: 00010283
> RAX: ffffffff84297c8a RBX: 0000000000008541 RCX: 0000000000100000
> RDX: ffffc9000e002000 RSI: 00000000000b63ac RDI: 00000000000b63ad
> RBP: 1ffff1100a622002 R08: ffffffff844d525f R09: 0000000000000002
> R10: 0000000000000003 R11: 0000000000000002 R12: 1ffff1100a62205e
> R13: ffff888053110010 R14: 0000000000000088 R15: ffff8880531102f0
> FS:  00007f529748d6c0(0000) GS:ffff88808d251000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fffb9f0fabc CR3: 0000000043ca6000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want to overwrite report's subsystems, reply with:
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> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 


#syz fix: bcachefs: Fix btree for nonexistent tree depth

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