Message-ID: <68a72860.050a0220.3d78fd.002a.GAE@google.com>
Date: Thu, 21 Aug 2025 07:08:32 -0700
From: syzbot <syzbot+a725ab460fc1def9896f@...kaller.appspotmail.com>
To: bigeasy@...utronix.de, brauner@...nel.org, jack@...e.cz, 
	linkinjeon@...nel.org, linux-ext4@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	sj1557.seo@...sung.com, syzkaller-bugs@...glegroups.com, tglx@...utronix.de, 
	viro@...iv.linux.org.uk
Subject: [syzbot] [exfat?] [ext4?] WARNING in __rt_mutex_slowlock_locked

Hello,

syzbot found the following issue on:

HEAD commit:    41cd3fd15263 Merge tag 'pci-v6.17-fixes-2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11ef37a2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e1e1566c7726877e
dashboard link: https://syzkaller.appspot.com/bug?extid=a725ab460fc1def9896f
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=17a857a2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14c916f0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bc397a2f4204/disk-41cd3fd1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5291086f4669/vmlinux-41cd3fd1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1099e6ad84b5/bzImage-41cd3fd1.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c1980868ad6b/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10e28fa2580000)

The issue was bisected to:

commit d2d6422f8bd17c6bb205133e290625a564194496
Author: Sebastian Andrzej Siewior <bigeasy@...utronix.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=16cf8fa2580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=15cf8fa2580000
console output: https://syzkaller.appspot.com/x/log.txt?x=11cf8fa2580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a725ab460fc1def9896f@...kaller.appspotmail.com
Fixes: d2d6422f8bd1 ("x86: Allow to enable PREEMPT_RT.")

exFAT-fs (loop0): Medium has reported failures. Some data may be lost.
exFAT-fs (loop0): failed to load upcase table (idx : 0x00010000, chksum : 0xe5674ec2, utbl_chksum : 0xe619d30d)
------------[ cut here ]------------
rtmutex deadlock detected
WARNING: CPU: 0 PID: 6000 at kernel/locking/rtmutex.c:1674 rt_mutex_handle_deadlock kernel/locking/rtmutex.c:1674 [inline]
WARNING: CPU: 0 PID: 6000 at kernel/locking/rtmutex.c:1674 __rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
WARNING: CPU: 0 PID: 6000 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: 6000 Comm: syz.0.17 Tainted: G        W           syzkaller #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 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 2c ee 5d 09 90 48 c7 c7 00 ed 0a 8b e8 df 89 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:ffffc900048df840 EFLAGS: 00010246
RAX: e12880a9366a4400 RBX: ffff8880324663e0 RCX: ffff888032465940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900048dfa30 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1017104863 R12: ffff888032467060
R13: ffff888032465958 R14: 1ffff1100648ce0c R15: dffffc0000000000
FS:  0000555557981500(0000) GS:ffff8881268c5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000035be0000 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_nested include/linux/fs.h:914 [inline]
 vfs_rename+0x68f/0xf00 fs/namei.c:5092
 do_renameat2+0x6ce/0xa80 fs/namei.c:5278
 __do_sys_renameat2 fs/namei.c:5312 [inline]
 __se_sys_renameat2 fs/namei.c:5309 [inline]
 __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5309
 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: 0033:0x7fc9cdd7ebe9
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:00007ffe70cc6ad8 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 00007fc9cdfa5fa0 RCX: 00007fc9cdd7ebe9
RDX: 0000000000000004 RSI: 00002000000001c0 RDI: 0000000000000004
RBP: 00007fc9cde01e19 R08: 0000000000000004 R09: 0000000000000000
R10: 0000200000000140 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc9cdfa5fa0 R14: 00007fc9cdfa5fa0 R15: 0000000000000005
 </TASK>


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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