[Devel] Re: [PATCH v3 03/16] slab: Ignore the cflgs bit in cache creation

[Christoph Lameter]

On Tue, 18 Sep 2012, Glauber Costa wrote:

> No cache should ever pass that as a creation flag, since this bit is
> used to mark an internal decision of the slab about object placement. We
> can just ignore this bit if it happens to be passed (such as when
> duplicating a cache in the kmem memcg patches)

If we do this then I would like to see a general masking of internal
allocator bits in kmem_cache_create. We could declare the highest byte to
be the internal slab flags. SLUB uses two flags in that area. SLAB uses
one.

F.e. add

#define SLAB_INTERNAL 0xFF00000000UL

to slab.h.

Then the flags can then be masked in mm/slab_common.c