On 17/01/2025 23:13, Christoph Lameter (Ampere) wrote:
> On Fri, 17 Jan 2025, Kevin Brodsky wrote:
>
>> index a29457bef626..3b07cdaac3ae 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -305,18 +305,6 @@ struct kmem_cache *__kmem_cache_create_args(const char *name,
>> goto out_unlock;
>> }
>>
>> - /* Refuse requests with allocator specific flags */
>> - if (flags & ~SLAB_FLAGS_PERMITTED) {
>> - err = -EINVAL;
>> - goto out_unlock;
>> - }
> I think we should keep checking for invalid flags.
The commit that introduced this check [1] aimed to ensure that no
allocator-specific flag is passed to kmem_cache_create(), so it seemed
to me it was no longer needed now that allocator-specific flags are gone.
Having said that, we could keep it in order to reject flags that are not
supposed to be passed to kmem_cache_create() (e.g. SLAB_SKIP_KFENCE).
With that approach we'd just need to clear SLAB_DEBUG_FLAGS below if
!CONFIG_SLUB_DEBUG (and get rid of CACHE_CREATE_MASK).
- Kevin
[1]
https://lore.kernel.org/all/1478553075-120242-2-git-send-email-thgarnie@xxxxxxxxxx/
>> - /*
>> - * Some allocators will constraint the set of valid flags to a subset
>> - * of all flags. We expect them to define CACHE_CREATE_MASK in this
>> - * case, and we'll just provide them with a sanitized version of the
>> - * passed flags.
>> - */
>> flags &= CACHE_CREATE_MASK;
> This would silently clear some flags instead of creating an error.
