Re: [PATCH v2 8/9] eventfs: moving tracing/events to eventfs

[Ajay Kaher]

> kernel test robot noticed "WARNING:at_fs/namei.c:#lookup_one_len" on:
>
> commit: 2fe2002efb23a715f5eb7a58891ff85f4e37b084 ("[PATCH v2 8/9] eventfs: moving tracing/events to eventfs")
> url: https://github.com/intel-lab-lkp/linux/commits/Ajay-Kaher/eventfs-introducing-struct-tracefs_inode/20230502-192949
> base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
> patch link: https://lore.kernel.org/all/1683026600-13485-9-git-send-email-akaher@xxxxxxxxxx/
> patch subject: [PATCH v2 8/9] eventfs: moving tracing/events to eventfs
.
.
.
>  49.752082][ T5878] eventfs_start_creating (fs/tracefs/inode.c:519) 
> [ 49.757416][ T5878] eventfs_create_dir (fs/tracefs/event_inode.c:187 (discriminator 3)) 
> [ 49.762488][ T5878] eventfs_root_lookup (fs/tracefs/event_inode.c:291) 
> [ 49.767637][ T5878] __lookup_slow (fs/namei.c:1686) 
> [ 49.772268][ T5878] walk_component (include/linux/fs.h:773 fs/namei.c:1704 fs/namei.c:1994) 
> [ 49.777016][ T5878] link_path_walk+0x24e/0x3b0 
> [ 49.783462][ T5878] ? path_init (fs/namei.c:2387) 
> [ 49.788021][ T5878] path_openat (fs/namei.c:3711) 
> [ 49.792463][ T5878] do_filp_open (fs/namei.c:3742) 
> [ 49.797021][ T5878] ? __check_object_size (mm/memremap.c:107 mm/memremap.c:144) 
> [ 49.803055][ T5878] do_sys_openat2 (fs/open.c:1348) 
> [ 49.807740][ T5878] __x64_sys_openat (fs/open.c:1375) 
> [ 49.812512][ T5878] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) 
> [ 49.817068][ T5878] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) 
> [   49.823092][ T5878] RIP: 0033:0x7fcddb3b84e7

Steve, locally I have reproduced this issue using:
    lkp run job-cpu-100%-uprobe-60s.yaml

And also fixed, I will include this fix as well in v3.

Thanks to lkp, kernel test robot <yujie.liu@xxxxxxxxx>.

-Ajay