linux-kernel - Re: [syzbot] [bcachefs?] kernel BUG in __bch2_trans

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Message-ID: <68ccf53d.050a0220.28a605.001a.GAE@google.com>
Date: Thu, 18 Sep 2025 23:16:29 -0700
From: syzbot <syzbot+3a42e4989f9047772c6d@...kaller.appspotmail.com>
To: 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_get

syzbot has found a reproducer for the following issue on:

HEAD commit:    c9d61056440c Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=14aa6534580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b8b6789b42526d72
dashboard link: https://syzkaller.appspot.com/bug?extid=3a42e4989f9047772c6d
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12f3e858580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11b6c712580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4f571468ab6f/disk-c9d61056.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3871c29d58eb/vmlinux-c9d61056.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dbc62ff54c5b/Image-c9d61056.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/257c55ab376d/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3a42e4989f9047772c6d@...kaller.appspotmail.com

bcachefs (loop0): /file3 offset 0: data_read_io_err
  u64s 7 type extent 1073741828:24:U32_MAX len 24 ver 0: durability: 1 crc: c_size 24 size 24 offset 0 nonce 0 csum crc32c 0:0  compress none ptr: 0:34:8 gen 0
bcachefs (loop0): /file3 offset 0: data read error: data_read_io_err
bcachefs (loop0): /file3 offset 0: data read error, data_read_io_err
  u64s 7 type extent 1073741828:24:U32_MAX len 24 ver 0: durability: 1 crc: c_size 24 size 24 offset 0 nonce 0 csum crc32c 0:0  compress none ptr: 0:34:8 gen 0
  loop0 io error
------------[ cut here ]------------
kernel BUG at fs/bcachefs/btree_iter.c:3462!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 14 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
Workqueue: events_unbound bch2_rbio_retry
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __bch2_trans_get+0x9ac/0x9d4 fs/bcachefs/btree_iter.c:3460
lr : __bch2_trans_get+0x9ac/0x9d4 fs/bcachefs/btree_iter.c:3460
sp : ffff800097c674a0
x29: ffff800097c674a0 x28: 1fffe0001d620840 x27: ffff0000c1a01e80
x26: dfff800000000000 x25: 0000000000000006 x24: ffff0000db4541d8
x23: 000000000000000e x22: ffff0000eb104200 x21: 0000000000000025
x20: ffff0000eb100000 x19: ffff0000d2510000 x18: 00000000ffffffff
x17: ffff800093529000 x16: ffff80008b01d6e0 x15: 0000000000000001
x14: 1ffff00012f8ce34 x13: 0000000000000000 x12: 0000000000000000
x11: ffff700012f8ce35 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000c1a01e80 x7 : ffff8000828bb454 x6 : 0000000000000000
x5 : ffff8000936f2db0 x4 : 0000000000000008 x3 : ffff800080522fb4
x2 : 0000000000000001 x1 : 0000000000000004 x0 : 0000000000000000
Call trace:
 __bch2_trans_get+0x9ac/0x9d4 fs/bcachefs/btree_iter.c:3460 (P)
 bch2_rbio_retry+0x17c/0xd44 fs/bcachefs/io_read.c:594
 bch2_rbio_punt fs/bcachefs/io_read.c:411 [inline]
 bch2_rbio_error+0x24c/0x354 fs/bcachefs/io_read.c:686
 bch2_read_endio+0x510/0x908 fs/bcachefs/io_read.c:-1
 bio_endio+0x858/0x894 block/bio.c:1651
 bch2_rbio_done fs/bcachefs/io_read.c:464 [inline]
 bch2_rbio_retry+0x86c/0xd44 fs/bcachefs/io_read.c:667
 process_one_work+0x7e8/0x155c kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x958/0xed8 kernel/workqueue.c:3400
 kthread+0x5fc/0x75c kernel/kthread.c:463
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844
Code: 17ffff25 9779d56a 17fffe9f 9779d568 (d4210000) 
---[ end trace 0000000000000000 ]---


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.