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

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

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