[v6.6] WARNING in ext4_journal_check_start

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=178db21a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=1b8918e16f1cb8a441e1
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=11936eb4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/82fd31b927a0/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=1372cec2580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1b8918...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 2950 at fs/ext4/ext4_jbd2.c:73 ext4_journal_check_start+0x1eb/0x250 fs/ext4/ext4_jbd2.c:73
Modules linked in:
CPU: 0 PID: 2950 Comm: kworker/u4:11 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:7)
RIP: 0010:ext4_journal_check_start+0x1eb/0x250 fs/ext4/ext4_jbd2.c:73
Code: 48 83 c4 08 41 bf e2 ff ff ff 44 89 f8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 62 d1 5b ff 41 bf fb ff ff ff eb e5 e8 55 d1 5b ff <0f> 0b eb d6 e8 4c d1 5b ff 0f 0b 43 80 7c 25 00 00 0f 85 0b ff ff
RSP: 0018:ffffc9000bd16db8 EFLAGS: 00010293
RAX: ffffffff8229bf6b RBX: ffff88805e2ee000 RCX: ffff88802b9f8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000a8e R08: ffff88805e2e0387 R09: 1ffff1100bc5c070
R10: dffffc0000000000 R11: ffffed100bc5c071 R12: dffffc0000000000
R13: 1ffff1100bc5dcc6 R14: ffff88805e2ee630 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc5e6a00218 CR3: 000000002665f000 CR4: 00000000003506f0
Call Trace:
<TASK>
__ext4_journal_start_sb+0x147/0x570 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_do_writepages+0xf92/0x38d0 fs/ext4/inode.c:2701
ext4_writepages+0x1a8/0x2f0 fs/ext4/inode.c:2807
do_writepages+0x3a2/0x600 mm/page-writeback.c:2575
__writeback_single_inode+0x153/0xee0 fs/fs-writeback.c:1635
writeback_sb_inodes+0x77c/0xef0 fs/fs-writeback.c:1926
__writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:1997
wb_writeback+0x464/0xba0 fs/fs-writeback.c:2107
wb_check_background_flush fs/fs-writeback.c:2177 [inline]
wb_do_writeback fs/fs-writeback.c:2265 [inline]
wb_workfn+0xb32/0xe20 fs/fs-writeback.c:2292
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


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