[syzbot] [fs?] WARNING: bad unlock balance in traverse

[syzbot <syzbot+0b16dd9bd622c40b2bbe@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ac9c34d1e45a Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165b9c98580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b1635bf4c5557b92
dashboard link: https://syzkaller.appspot.com/bug?extid=0b16dd9bd622c40b2bbe
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=152b003f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed21c75da715/disk-ac9c34d1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f51096fe566c/vmlinux-ac9c34d1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e6a27961fbbe/bzImage-ac9c34d1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0b16dd9bd622c40b2bbe@syzkaller.appspotmail.com

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:00007ffdab0827c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007f06103a5fa0 RCX: 00007f061018d169
RDX: 0000000000000400 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffdab082820 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009871 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f06103a5fa0 R14: 00007f06103a5fa0 R15: 0000000000000004
 </TASK>
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Not tainted
-------------------------------------
syz.0.17/6067 is trying to release lock (event_mutex) at:
[<ffffffff82399e2d>] traverse.part.0.constprop.0+0x2bd/0x640 fs/seq_file.c:131
but there are no more locks to release!

other info that might help us debug this:
1 lock held by syz.0.17/6067:
 #0: ffff888032e872f0 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xd8/0x12b0 fs/seq_file.c:182

stack backtrace:
CPU: 1 UID: 0 PID: 6067 Comm: syz.0.17 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_unlock_imbalance_bug kernel/locking/lockdep.c:5289 [inline]
 print_unlock_imbalance_bug+0x1aa/0x1f0 kernel/locking/lockdep.c:5263
 __lock_release kernel/locking/lockdep.c:5528 [inline]
 lock_release+0x525/0x6f0 kernel/locking/lockdep.c:5872
 __mutex_unlock_slowpath+0xa3/0x6a0 kernel/locking/mutex.c:891
 traverse.part.0.constprop.0+0x2bd/0x640 fs/seq_file.c:131
 traverse fs/seq_file.c:98 [inline]
 seq_read_iter+0x934/0x12b0 fs/seq_file.c:195
 seq_read+0x39f/0x4e0 fs/seq_file.c:162
 vfs_read+0x1df/0xbf0 fs/read_write.c:563
 ksys_pread64 fs/read_write.c:756 [inline]
 __do_sys_pread64 fs/read_write.c:764 [inline]
 __se_sys_pread64 fs/read_write.c:761 [inline]
 __x64_sys_pread64+0x1f6/0x250 fs/read_write.c:761
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f061018d169
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:00007ffdab0827c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007f06103a5fa0 RCX: 00007f061018d169
RDX: 0000000000000400 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffdab082820 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009871 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f06103a5fa0 R14: 00007f06103a5fa0 R15: 0000000000000004
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	ff c3                	inc    %ebx
   2:	66 2e 0f 1f 84 00 00 	cs nopw 0x0(%rax,%rax,1)
   9:	00 00 00
   c:	0f 1f 40 00          	nopl   0x0(%rax)
  10:	48 89 f8             	mov    %rdi,%rax
  13:	48 89 f7             	mov    %rsi,%rdi
  16:	48 89 d6             	mov    %rdx,%rsi
  19:	48 89 ca             	mov    %rcx,%rdx
  1c:	4d 89 c2             	mov    %r8,%r10
  1f:	4d 89 c8             	mov    %r9,%r8
  22:	4c 8b 4c 24 08       	mov    0x8(%rsp),%r9
  27:	0f 05                	syscall
* 29:	48 3d 01 f0 ff ff    	cmp    $0xfffffffffffff001,%rax <-- trapping instruction
  2f:	73 01                	jae    0x32
  31:	c3                   	ret
  32:	48 c7 c1 a8 ff ff ff 	mov    $0xffffffffffffffa8,%rcx
  39:	f7 d8                	neg    %eax
  3b:	64 89 01             	mov    %eax,%fs:(%rcx)
  3e:	48                   	rex.W


---
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