slub: Commonize slab_cache field in struct page

Right now, slab and slub have fields in struct page to derive which
cache a page belongs to, but they do it slightly differently.

slab uses a field called slab_cache, that lives in the third double
word. slub, uses a field called "slab", living outside of the
doublewords area.

Ideally, we could use the same field for this. Since slub heavily makes
use of the doubleword region, there isn't really much room to move
slub's slab_cache field around. Since slab does not have such strict
placement restrictions, we can move it outside the doubleword area.

The naming used by slab, "slab_cache", is less confusing, and it is
preferred over slub's generic "slab".

Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 31f8a3af7d94..2fef4e720e79 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -128,10 +128,7 @@ struct page {
                 };
 
                 struct list_head list;  /* slobs list of pages */
-                struct {                /* slab fields */
-                        struct kmem_cache *slab_cache;
-                        struct slab *slab_page;
-                };
+                struct slab *slab_page; /* slab fields */
         };
 
         /* Remainder is not double word aligned */
@@ -146,7 +143,7 @@ struct page {
 #if USE_SPLIT_PTLOCKS
                 spinlock_t ptl;
 #endif
-                struct kmem_cache *slab;        /* SLUB: Pointer to slab */
+                struct kmem_cache *slab_cache;  /* SL[AU]B: Pointer to slab */
                 struct page *first_page;        /* Compound tail pages */
         };