linux-kernel - [syzbot] [bcachefs?] kernel BUG in __journal_res

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Message-ID: <6852ba08.050a0220.216029.0010.GAE@google.com>
Date: Wed, 18 Jun 2025 06:07:20 -0700
From: syzbot <syzbot+b58cefdc75f590b71819@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] kernel BUG in __journal_res_get (3)

Hello,

syzbot found the following issue on:

HEAD commit:    4774cfe3543a Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=163ade0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb55ce02d42a1797
dashboard link: https://syzkaller.appspot.com/bug?extid=b58cefdc75f590b71819
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14ba25d4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16e1710c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/97bb82d143d5/disk-4774cfe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/705549b5d0ef/vmlinux-4774cfe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/49a4d858182e/bzImage-4774cfe3.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/641c4a3837a4/mount_0.gz

Bisection is inconclusive: the first bad commit could be any of:

0e43bf5a6a8f bcachefs: Simplify logic
58c36e6710d3 bcachefs: Initialize c->name earlier on single dev filesystems
c02e5b57283a bcachefs: Single device mode

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1348290c580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b58cefdc75f590b71819@...kaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/bcachefs/journal.c:397!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 5845 Comm: syz-executor388 Not tainted 6.16.0-rc1-syzkaller-00203-g4774cfe3543a #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:journal_entry_open fs/bcachefs/journal.c:397 [inline]
RIP: 0010:__journal_res_get+0x25cd/0x27f0 fs/bcachefs/journal.c:639
Code: ff ff e9 2b db ff ff e8 01 7c 7e fd 41 be eb f6 ff ff e9 1b db ff ff e8 11 58 1d 07 e8 ec 7b 7e fd 90 0f 0b e8 e4 7b 7e fd 90 <0f> 0b e8 dc 7b 7e fd 90 0f 0b e8 d4 7b 7e fd 90 0f 0b e8 cc 7b 7e
RSP: 0018:ffffc900044af4c0 EFLAGS: 00010293
RAX: ffffffff8441cf5c RBX: 1ffff1100dda951b RCX: ffff888011a10000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffffc900044af790 R08: ffff88806ed4a9f7 R09: 1ffff1100dda953e
R10: dffffc0000000000 R11: ffffed100dda953f R12: ffff88806ed49800
R13: 1ffff1100dda953e R14: 0000000000000002 R15: 00000000007ffffe
FS:  00007f2e8034d6c0(0000) GS:ffff888125d86000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2e803ec758 CR3: 0000000074850000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 bch2_journal_res_get_slowpath+0xdc/0xaf0 fs/bcachefs/journal.c:734
 bch2_journal_res_get+0x14f/0x1f0 fs/bcachefs/journal.h:401
 __bch2_journal_meta+0x40/0x1d0 fs/bcachefs/journal.c:980
 bch2_fs_journal_stop+0x1dd/0x440 fs/bcachefs/journal.c:1462
 __bch2_fs_read_only+0x343/0x5b0 fs/bcachefs/super.c:307
 __bch2_fs_read_write+0x5cd/0x830 fs/bcachefs/super.c:554
 bch2_fs_reconfigure+0x29a/0x400 fs/bcachefs/fs.c:2675
 reconfigure_super+0x224/0x890 fs/super.c:1075
 do_remount fs/namespace.c:3369 [inline]
 path_mount+0xd18/0xfe0 fs/namespace.c:4201
 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: 0033:0x7f2e80398c49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2e8034d218 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2e804306a8 RCX: 00007f2e80398c49
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f2e804306a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002012024 R11: 0000000000000246 R12: 0000200000000000
R13: 0030656c69662f2e R14: 7366656863616362 R15: 0000200000000080
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:journal_entry_open fs/bcachefs/journal.c:397 [inline]
RIP: 0010:__journal_res_get+0x25cd/0x27f0 fs/bcachefs/journal.c:639
Code: ff ff e9 2b db ff ff e8 01 7c 7e fd 41 be eb f6 ff ff e9 1b db ff ff e8 11 58 1d 07 e8 ec 7b 7e fd 90 0f 0b e8 e4 7b 7e fd 90 <0f> 0b e8 dc 7b 7e fd 90 0f 0b e8 d4 7b 7e fd 90 0f 0b e8 cc 7b 7e
RSP: 0018:ffffc900044af4c0 EFLAGS: 00010293
RAX: ffffffff8441cf5c RBX: 1ffff1100dda951b RCX: ffff888011a10000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffffc900044af790 R08: ffff88806ed4a9f7 R09: 1ffff1100dda953e
R10: dffffc0000000000 R11: ffffed100dda953f R12: ffff88806ed49800
R13: 1ffff1100dda953e R14: 0000000000000002 R15: 00000000007ffffe
FS:  00007f2e8034d6c0(0000) GS:ffff888125d86000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2e803ec758 CR3: 0000000074850000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This report is generated by a bot. It may contain errors.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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#syz dup: exact-subject-of-another-report

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#syz undup