Re: [PATCH] mm/slab: fix probable issue of dentries registration under /sys/kernel/slab

[Vladimir Zapolskiy]

Hi Hao,

On 5/20/26 06:21, Hao Li wrote:
> On Wed, May 20, 2026 at 04:10:19AM +0300, Vladimir Zapolskiy wrote:
> > L2TP/IP and L2TP/IPv6 protocol names contain a slash symbol, however these
> > names are blindly used as symlinks to slab cache objects registered under
> > /sys/kernel/slab. This kind of symlink creation is successful, but its
> > dentry is obviously broken, as well it breaks the access to the list of
> > /sys/kernel/slab dentries.
> >
> > Likely L2TP protocol renames cannot be done, since the defined protocol
> > names are exposed over /proc/net/protocols for years, but the symlink
> > names can be renamed, because they are yet to be properly created, and
> > this should be eventually done by this change.
> >
> > The problem manifests itself, if CONFIG_L2TP_IP build symbol is selected.
>
> Hello, thanks for the patch.
>
> Could L2TP possibly be loaded as a module? I noticed that
> __kmem_cache_create_args can also call into sysfs_slab_alias. If L2TP is loaded
> as a module after boot and dynamically creates a slub cache, it may bypass your
> fix..

you're totally right, __kmem_cache_create_args execution path should also
be fixed, I'll send v2.

Thank you for review!

--
Best wishes,
Vladimir