linux-kernel - Re: [syzbot] [bcachefs?] kernel BUG in bch2_trans_update_by

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Message-ID: <686afd3c.a00a0220.c7b3.0067.GAE@google.com>
Date: Sun, 06 Jul 2025 15:48:28 -0700
From: syzbot <syzbot+210dfbddd64294066983@...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_update_by_path

syzbot has found a reproducer for the following issue on:

HEAD commit:    7482bb149b9f 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=1675e582580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3c06e3e2454512b3
dashboard link: https://syzkaller.appspot.com/bug?extid=210dfbddd64294066983
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1412628c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d5ef70580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f623d741d651/disk-7482bb14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483e23ae71b1/vmlinux-7482bb14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/79b5baaa1b50/Image-7482bb14.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/da659f915c60/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+210dfbddd64294066983@...kaller.appspotmail.com

bcachefs (loop0): bucket 0:34 gen 0 data type need_discard has wrong dirty_sectors: got 16, should be 0, fixing
 done
bcachefs (loop0): going read-write
bcachefs (loop0): journal_replay...
------------[ cut here ]------------
kernel BUG at fs/bcachefs/btree_update.c:375!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 6741 Comm: syz.0.16 Not tainted 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : bch2_trans_update_by_path+0x17bc/0x17f0 fs/bcachefs/btree_update.c:375
lr : bch2_trans_update_by_path+0x17bc/0x17f0 fs/bcachefs/btree_update.c:375
sp : ffff80009e1165c0
x29: ffff80009e116780 x28: 0000000000008540 x27: ffff0000c34aca80
x26: ffff0000ec7e0000 x25: ffff700013c22ce0 x24: 1fffe0001d8fc002
x23: ffff0000ec7e0010 x22: ffff0000ec7e02f0 x21: 1fffe0001d8fc05e
x20: dfff800000000000 x19: ffff0000eb400000 x18: 00000000ffffffff
x17: ffff800093363000 x16: ffff80008aefca08 x15: 0000000000000003
x14: 0000000000000000 x13: 0000000000000003 x12: 0000000000ff0100
x11: ffff0000c8ae3d00 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000c8ae3d00 x7 : ffffffffffffffff x6 : ffffffffffffffff
x5 : ffff0000ec7e02f0 x4 : ffff800082a4ca28 x3 : 0000000000180000
x2 : ffff0000c34aca80 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 bch2_trans_update_by_path+0x17bc/0x17f0 fs/bcachefs/btree_update.c:375 (P)
 bch2_trans_update_ip+0x7bc/0x17ec fs/bcachefs/btree_update.c:531
 bch2_trans_update+0x4c/0x60 fs/bcachefs/btree_update.h:123
 bch2_journal_replay_key+0x348/0x68c fs/bcachefs/recovery.c:311
 bch2_journal_replay+0xfdc/0x1c44 fs/bcachefs/recovery.c:396
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x29c/0xd18 fs/bcachefs/recovery_passes.c:539
 bch2_run_recovery_passes+0x174/0x1f4 fs/bcachefs/recovery_passes.c:610
 bch2_fs_recovery+0x1c34/0x2fb4 fs/bcachefs/recovery.c:1005
 bch2_fs_start+0x914/0xbc0 fs/bcachefs/super.c:1212
 bch2_fs_get_tree+0x880/0x1030 fs/bcachefs/fs.c:2490
 vfs_get_tree+0x90/0x28c fs/super.c:1804
 do_new_mount+0x228/0x814 fs/namespace.c:3902
 path_mount+0x5b4/0xde0 fs/namespace.c:4226
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount fs/namespace.c:4427 [inline]
 __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4427
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Code: 17fffe3f 977aae52 d4210000 977aae50 (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.