[v6.6] WARNING in reiserfs_lookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 147338df3487 Linux 6.6.108
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10105ce2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=58f6935ad913305afffd
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/23d0a7436789/disk-147338df.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5658c8bd0cce/vmlinux-147338df.xz
kernel image: https://storage.googleapis.com/syzbot-assets/be243abccdbe/bzImage-147338df.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+58f693...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
... Log Wrap ... Log Wrap ... Log Wrap ...
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 0 PID: 6207 at kernel/locking/mutex.c:582 __mutex_lock_common kernel/locking/mutex.c:582 [inline]
WARNING: CPU: 0 PID: 6207 at kernel/locking/mutex.c:582 __mutex_lock+0xb8c/0xcc0 kernel/locking/mutex.c:747
Modules linked in:
CPU: 0 PID: 6207 Comm: syz.0.14103 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:582 [inline]
RIP: 0010:__mutex_lock+0xb8c/0xcc0 kernel/locking/mutex.c:747
Code: 04 08 84 c0 0f 85 20 01 00 00 83 3d 4d c0 d3 03 00 0f 85 81 f5 ff ff 48 c7 c7 40 a7 aa 8a 48 c7 c6 e0 a7 aa 8a e8 a4 17 d9 f6 <0f> 0b e9 67 f5 ff ff 0f 0b e9 47 f9 ff ff 0f 0b e9 ff f5 ff ff 48
RSP: 0018:ffffc9000c60f540 EFLAGS: 00010246
RAX: 2ec3fa7556c0d500 RBX: ffff88802429d828 RCX: 0000000000080000
RDX: ffffc900128f9000 RSI: 0000000000003ea4 RDI: 0000000000003ea5
RBP: ffffc9000c60f6a0 R08: ffff8880b8e28c13 R09: 1ffff110171c5182
R10: dffffc0000000000 R11: ffffed10171c5183 R12: 0000000000000000
R13: 1ffff920018c1eb8 R14: dffffc0000000000 R15: 0000000000000000
FS: 00007fd7fd87c6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33f1fff8 CR3: 000000005f222000 CR4: 00000000003506f0
Call Trace:
<TASK>
reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x151/0x520 fs/reiserfs/namei.c:364
__lookup_slow+0x281/0x3b0 fs/namei.c:1694
lookup_slow+0x53/0x70 fs/namei.c:1711
walk_component+0x2be/0x3f0 fs/namei.c:2002
lookup_last fs/namei.c:2459 [inline]
path_lookupat+0x169/0x440 fs/namei.c:2483
filename_lookup+0x1f4/0x510 fs/namei.c:2512
user_path_at_empty+0x42/0x60 fs/namei.c:2909
user_path_at include/linux/namei.h:57 [inline]
path_removexattr+0x11f/0x3f0 fs/xattr.c:924
__do_sys_removexattr fs/xattr.c:943 [inline]
__se_sys_removexattr fs/xattr.c:940 [inline]
__x64_sys_removexattr+0x60/0x70 fs/xattr.c:940
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd7fc98eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd7fd87c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000c5
RAX: ffffffffffffffda RBX: 00007fd7fcbe5fa0 RCX: 00007fd7fc98eec9
RDX: 0000000000000000 RSI: 0000200000000a40 RDI: 0000200000000480
RBP: 00007fd7fca11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd7fcbe6038 R14: 00007fd7fcbe5fa0 R15: 00007ffc40109388
</TASK>


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