[v6.6] WARNING in hfsplus_ext_write_extent

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cbb31f77b879 Linux 6.6.121
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1690d7fc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=1e9e06cbbf68757b56a3
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6436cbae3604/disk-cbb31f77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8f3a3d318f99/vmlinux-cbb31f77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/84920a2a012f/bzImage-cbb31f77.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e9e06...@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 0 PID: 4347 at kernel/locking/mutex.c:582 __mutex_lock_common kernel/locking/mutex.c:582 [inline]
WARNING: CPU: 0 PID: 4347 at kernel/locking/mutex.c:582 __mutex_lock+0xb85/0xcc0 kernel/locking/mutex.c:747
Modules linked in:
CPU: 0 PID: 4347 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-7:2)

RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:582 [inline]
RIP: 0010:__mutex_lock+0xb85/0xcc0 kernel/locking/mutex.c:747
Code: 04 08 84 c0 0f 85 27 01 00 00 83 3d 94 58 fe 03 00 0f 85 95 f5 ff ff 48 c7 c7 a0 b3 ca 8a 48 c7 c6 40 b4 ca 8a e8 4b 21 c4 f6 <0f> 0b e9 7b f5 ff ff 0f 0b e9 5f f9 ff ff 0f 0b e9 18 f6 ff ff e8
RSP: 0018:ffffc9000ea47220 EFLAGS: 00010246
RAX: f9620a9a359ba900 RBX: ffff88805e10b580 RCX: ffff8880302ebc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9000ea47370 R08: ffffc9000ea46e27 R09: 1ffff92001d48dc4
R10: dffffc0000000000 R11: fffff52001d48dc5 R12: 0000000000000000
R13: 1ffff92001d48e54 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5a8ed88000 CR3: 000000001b79b000 CR4: 00000000003506f0
Call Trace:
<TASK>
hfsplus_ext_write_extent+0x91/0x230 fs/hfsplus/extents.c:149
hfsplus_write_inode+0x22/0x5e0 fs/hfsplus/super.c:167
write_inode fs/fs-writeback.c:1483 [inline]
__writeback_single_inode+0x705/0xec0 fs/fs-writeback.c:1700
writeback_sb_inodes+0x7cd/0xf50 fs/fs-writeback.c:1926
wb_writeback+0x46a/0xbf0 fs/fs-writeback.c:2105
wb_do_writeback fs/fs-writeback.c:2252 [inline]
wb_workfn+0x400/0xe60 fs/fs-writeback.c:2292
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa5d/0x15d0 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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