------------[ 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.0.0/5318
Modules linked in:
CPU: 0 UID: 0 PID: 5318 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 40 e3 11 8f 48 89 de 48 c7 c2 80 6d da 83 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d e9 c2 ea d0 fd e8 cd a0 ec fd 90 <0f> 0b 90 e9 c7 fd ff ff e8 bf a0 ec fd 90 0f 0b 90 48 b8 00 00 00
RSP: 0000:ffffc9000f407a88 EFLAGS: 00010287
RAX: ffffffff83da7113 RBX: ffff888044047d10 RCX: 0000000000100000
RDX: ffffc90020802000 RSI: 000000000003f4b3 RDI: 000000000003f4b4
RBP: ffff888044047d00 R08: 00000000ffffffff R09: 1ffffffff20af686
R10: dffffc0000000000 R11: fffffbfff20af687 R12: 0000000000000000
R13: ffff888013208800 R14: ffff888044047d00 R15: 0000000000000003
FS:  00007fa3de7f36c0(0000) GS:ffff88808c53e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3e39a2f20 CR3: 000000001226d000 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: 0033:0x7fa3e2b9e0d9
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:00007fa3de7f2fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fa3e2e26270 RCX: 00007fa3e2b9e0d9
RDX: 00000000000001ff RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007fa3e2c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3e2e26308 R14: 00007fa3e2e26270 R15: 00007ffc01ca5528
 </TASK>