[moderation] [trace?] [fs?] WARNING in free_ei

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d3ae59288f1 Linux 7.2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11932679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ead6a6de2292ff28
dashboard link: https://syzkaller.appspot.com/bug?extid=cafb733a6adbecdbfd4d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org linux-tra...@vger.kernel.org mathieu....@efficios.com mhir...@kernel.org ros...@goodmis.org]

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-8d3ae592.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/01477d2b0cb0/vmlinux-8d3ae592.xz
kernel image: https://storage.googleapis.com/syzbot-assets/59a221d8a248/bzImage-8d3ae592.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cafb73...@syzkaller.appspotmail.com

oom_control is deprecated and will be removed. Please report your usecase to linu...@kvack.org if you depend on this functionality.
socket: no more sockets
Could not create tracefs 'show_event_filters' entry
Could not create tracefs 'show_event_triggers' entry
Could not create tracefs 'set_event_pid' entry
Could not create tracefs 'set_event_notrace_pid' entry
------------[ cut here ]------------
!list_empty(&ei->children)
WARNING: fs/tracefs/event_inode.c:128 at free_ei+0x284/0x340 fs/tracefs/event_inode.c:128, CPU#0: syz.0.0/5305
Modules linked in:
CPU: 0 UID: 0 PID: 5305 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:free_ei+0x284/0x340 fs/tracefs/event_inode.c:128
Code: 48 c7 c7 80 e3 11 8f 48 89 de 48 c7 c2 10 7b da 83 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d e9 32 dd d0 fd e8 5d 93 ec fd 90 <0f> 0b 90 e9 c7 fd ff ff e8 4f 93 ec fd 90 0f 0b 90 48 b8 00 00 00
RSP: 0018:ffffc9000dcefa88 EFLAGS: 00010283
RAX: ffffffff83da7ea3 RBX: ffff888012eb5d10 RCX: 0000000000100000
RDX: ffffc9000eb32000 RSI: 00000000000a2ed8 RDI: 00000000000a2ed9
RBP: ffff888012eb5d00 R08: 00000000ffffffff R09: 1ffffffff20af686
R10: dffffc0000000000 R11: fffffbfff20af687 R12: 0000000000000000
R13: ffff88800e71c000 R14: ffff888012eb5d00 R15: 0000000000000003
FS: 00007fe72b47c6c0(0000) GS:ffff88808c53e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efebd253ad8 CR3: 0000000040258000 CR4: 0000000000352ef0
Call Trace:
<TASK>
cleanup_ei fs/tracefs/event_inode.c:150 [inline]
eventfs_create_events_dir+0x7c4/0x9f0 fs/tracefs/event_inode.c:834
create_event_toplevel_files+0x11e/0x1a0 kernel/trace/trace_events.c:4593
event_trace_add_tracer+0x8a/0x3b0 kernel/trace/trace_events.c:4624
trace_array_create_dir+0x77/0x160 kernel/trace/trace.c:8548
trace_array_create_systems+0xb3c/0xe60 kernel/trace/trace.c:8639
trace_array_create kernel/trace/trace.c:8666 [inline]
instance_mkdir+0xd5/0x140 kernel/trace/trace.c:8681
tracefs_syscall_mkdir+0x11a/0x190 fs/tracefs/inode.c:121
vfs_mkdir+0x406/0x620 fs/namei.c:5276
filename_mkdirat+0x285/0x510 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat+0x35/0x150 fs/namei.c:5327
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe72a59e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe72b47bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fe72a825fa0 RCX: 00007fe72a59e0d9
RDX: 00000000000001ff RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007fe72a635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe72a826038 R14: 00007fe72a825fa0 R15: 00007ffd503d8cd8
</TASK>


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