[Devel] Re: [PATCH v5] slab: Ignore internal flags in cache creation

[David Rientjes]

On Wed, 17 Oct 2012, Glauber Costa wrote:

> Some flags are used internally by the allocators for management
> purposes. One example of that is the CFLGS_OFF_SLAB flag that slab uses
> to mark that the metadata for that cache is stored outside of the slab.
> 
> No cache should ever pass those as a creation flags. We can just ignore
> this bit if it happens to be passed (such as when duplicating a cache in
> the kmem memcg patches).
> 
> Because such flags can vary from allocator to allocator, we allow them
> to make their own decisions on that, defining SLAB_AVAILABLE_FLAGS with
> all flags that are valid at creation time.  Allocators that doesn't have
> any specific flag requirement should define that to mean all flags.
> 
> Common code will mask out all flags not belonging to that set.
> 
> [ v2: leave the mask out decision up to the allocators ]
> [ v3: define flags for all allocators ]
> [ v4: move all definitions to slab.h ]
> 
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> Acked-by: Christoph Lameter <cl at linux.com>
> CC: David Rientjes <rientjes at google.com>
> CC: Pekka Enberg <penberg at cs.helsinki.fi>

Acked-by: David Rientjes <rientjes at google.com>