[syzbot] [exfat?] WARNING in __rt_mutex_slowlock_locked (2)

[syzbot <syzbot+5216036fc59c43d1ee02@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    c2c2ccfd4ba7 Merge tag 'net-6.18-rc5' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=151be114580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=41ad820f608cb833
dashboard link: https://syzkaller.appspot.com/bug?extid=5216036fc59c43d1ee02
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=11062a58580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16e19084580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/121c46acc3df/disk-c2c2ccfd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eb0aef8fb7a1/vmlinux-c2c2ccfd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a2bba0757aa5/bzImage-c2c2ccfd.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/03760a9baabf/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=12084532580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5216036fc59c43d1ee02@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 256
exFAT-fs (loop0): start_clu is invalid cluster(0x400)
------------[ cut here ]------------
rtmutex deadlock detected
WARNING: CPU: 0 PID: 6071 at kernel/locking/rtmutex.c:1674 rt_mutex_handle_deadlock kernel/locking/rtmutex.c:1674 [inline]
WARNING: CPU: 0 PID: 6071 at kernel/locking/rtmutex.c:1674 __rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
WARNING: CPU: 0 PID: 6071 at kernel/locking/rtmutex.c:1674 __rt_mutex_slowlock_locked+0xed2/0x25e0 kernel/locking/rtmutex.c:1760
Modules linked in:
CPU: 0 UID: 0 PID: 6071 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:rt_mutex_handle_deadlock kernel/locking/rtmutex.c:1674 [inline]
RIP: 0010:__rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
RIP: 0010:__rt_mutex_slowlock_locked+0xed2/0x25e0 kernel/locking/rtmutex.c:1760
Code: 7c 24 20 dd 4c 8b b4 24 98 00 00 00 0f 85 fd 0a 00 00 48 8b 7c 24 10 e8 4c 50 28 09 90 48 c7 c7 60 fd ea 8a e8 ef 62 e7 ff 90 <0f> 0b 90 90 48 8b 9c 24 80 00 00 00 43 80 3c 3e 00 74 08 4c 89 e7
RSP: 0018:ffffc90003d87a20 EFLAGS: 00010246
RAX: 5bae39e042a2bb00 RBX: ffff88802472e4e0 RCX: ffff88802472da00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003d87c10 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed101710487b R12: ffff88802472f160
R13: ffff88802472da18 R14: 1ffff110048e5e2c R15: dffffc0000000000
FS:  00005555931b8500(0000) GS:ffff888126df9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffefdd79178 CR3: 000000003e14c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rt_mutex_slowlock+0xb5/0x160 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 rwbase_write_lock+0x14f/0x750 kernel/locking/rwbase_rt.c:244
 inode_lock include/linux/fs.h:980 [inline]
 vfs_rmdir+0xf7/0x520 fs/namei.c:4537
 do_rmdir+0x25f/0x550 fs/namei.c:4603
 __do_sys_unlinkat fs/namei.c:4777 [inline]
 __se_sys_unlinkat fs/namei.c:4771 [inline]
 __x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:4771
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f03a63ff6c9
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:00007ffd1d6ca228 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f03a6655fa0 RCX: 00007f03a63ff6c9
RDX: 0000000000000200 RSI: 0000200000000040 RDI: 0000000000000006
RBP: 00007f03a6481f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f03a6655fa0 R14: 00007f03a6655fa0 R15: 0000000000000003
 </TASK>


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