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

[Hao Li]

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..

-- 
Thanks,
Hao