[syzbot] [hfs?] WARNING in hfs_find_init

[syzbot <syzbot+6a141f31cc9495a3dcc1@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    dfd4b508c8c6 Merge tag 'drm-fixes-2025-08-16' of https://g..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13c6f3a2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=98e114f4eb77e551
dashboard link: https://syzkaller.appspot.com/bug?extid=6a141f31cc9495a3dcc1
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=135edaf0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100ad3a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/289d8459a101/disk-dfd4b508.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/653f0f06a0ea/vmlinux-dfd4b508.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ab9bdbe6030/bzImage-dfd4b508.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/69f46f8377ed/mount_0.gz

The issue was bisected to:

commit d2d6422f8bd17c6bb205133e290625a564194496
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Fri Sep 6 10:59:04 2024 +0000

    x86: Allow to enable PREEMPT_RT.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=119b63a2580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=139b63a2580000
console output: https://syzkaller.appspot.com/x/log.txt?x=159b63a2580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6a141f31cc9495a3dcc1@syzkaller.appspotmail.com
Fixes: d2d6422f8bd1 ("x86: Allow to enable PREEMPT_RT.")

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
------------[ cut here ]------------
rtmutex deadlock detected
WARNING: CPU: 1 PID: 5838 at kernel/locking/rtmutex.c:1674 rt_mutex_handle_deadlock+0x28/0xb0 kernel/locking/rtmutex.c:1674
Modules linked in:
CPU: 1 UID: 0 PID: 5838 Comm: syz-executor124 Tainted: G        W           6.17.0-rc1-syzkaller-00199-gdfd4b508c8c6 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rt_mutex_handle_deadlock+0x28/0xb0 kernel/locking/rtmutex.c:1674
Code: 90 90 41 57 41 56 41 55 41 54 53 83 ff dd 0f 85 8c 00 00 00 48 89 f7 e8 c6 2c 01 00 90 48 c7 c7 00 09 0b 8b e8 79 d8 8a f6 90 <0f> 0b 90 90 4c 8d 3d 00 00 00 00 65 48 8b 1c 25 08 b0 f5 91 4c 8d
RSP: 0018:ffffc90004b0ec90 EFLAGS: 00010246
RAX: 8abe693e197be100 RBX: ffffc90004b0ed20 RCX: ffff88803d511dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90004b0ee28 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1017124863 R12: 1ffff92000961da0
R13: ffffffff8af85119 R14: ffff88803d528048 R15: dffffc0000000000
FS:  000055555dc68380(0000) GS:ffff8881269c5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000002fe82000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x692/0x6e0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
 mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
 hfs_find_init+0x184/0x200 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x2ee/0x1230 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x316/0x1230 fs/hfs/extent.c:401
 hfs_get_block+0x3d7/0xbd0 fs/hfs/extent.c:353
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin fs/buffer.c:2256 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2594
 hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:52
 cont_expand_zero fs/buffer.c:2522 [inline]
 cont_write_begin+0x2fd/0xb50 fs/buffer.c:2584
 hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:52
 hfs_file_truncate+0x190/0x9c0 fs/hfs/extent.c:494
 hfs_inode_setattr+0x4a9/0x670 fs/hfs/inode.c:654
 notify_change+0xb31/0xe60 fs/attr.c:552
 do_truncate+0x1a4/0x220 fs/open.c:68
 vfs_truncate+0x493/0x520 fs/open.c:118
 do_sys_truncate+0xdb/0x190 fs/open.c:141
 __do_sys_truncate fs/open.c:153 [inline]
 __se_sys_truncate fs/open.c:151 [inline]
 __x64_sys_truncate+0x5b/0x70 fs/open.c:151
 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: 0033:0x7fa1dc925b99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff5e8c2808 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007fa1dc925b99
RDX: 00007fa1dc925b99 RSI: 0000000001001bfc RDI: 0000200000000040
RBP: 00007fa1dc9995f0 R08: 000055555dc694c0 R09: 000055555dc694c0
R10: 000055555dc694c0 R11: 0000000000000246 R12: 00007fff5e8c2830
R13: 00007fff5e8c2a58 R14: 431bde82d7b634db R15: 00007fa1dc96e03b
 </TASK>


---
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