Merge branch 'slab/struct-page' into slab/next

3 files changed, 26 insertions, 11 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index faf4b7c1ad12..95bf0c5a7eb9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -42,18 +42,22 @@ struct page {
         /* First double word block */
         unsigned long flags;            /* Atomic flags, some possibly
                                          * updated asynchronously */
-        struct address_space *mapping;  /* If low bit clear, points to
-                                         * inode address_space, or NULL.
-                                         * If page mapped as anonymous
-                                         * memory, low bit is set, and
-                                         * it points to anon_vma object:
-                                         * see PAGE_MAPPING_ANON below.
-                                         */
+        union {
+                struct address_space *mapping;  /* If low bit clear, points to
+                                                 * inode address_space, or NULL.
+                                                 * If page mapped as anonymous
+                                                 * memory, low bit is set, and
+                                                 * it points to anon_vma object:
+                                                 * see PAGE_MAPPING_ANON below.
+                                                 */
+                void *s_mem;                    /* slab first object */
+        };
+
         /* Second double word */
         struct {
                 union {
                         pgoff_t index;          /* Our offset within mapping. */
-                        void *freelist;         /* slub/slob first free object */
+                        void *freelist;         /* sl[aou]b first free object */
                         bool pfmemalloc;        /* If set by the page allocator,
                                                  * ALLOC_NO_WATERMARKS was set
                                                  * and the low watermark was not
@@ -109,6 +113,7 @@ struct page {
                                 };
                                 atomic_t _count;                /* Usage count, see below. */
                         };
+                        unsigned int active;    /* SLAB */
                 };
         };
 
@@ -130,6 +135,9 @@ struct page {
 
                 struct list_head list;  /* slobs list of pages */
                 struct slab *slab_page; /* slab fields */
+                struct rcu_head rcu_head;       /* Used by SLAB
+                                                 * when destroying via RCU
+                                                 */
         };
 
         /* Remainder is not double word aligned */
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6c5cc0ea8713..caaad51fee1f 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -51,7 +51,14 @@
  *  }
  *  rcu_read_unlock();
  *
- * See also the comment on struct slab_rcu in mm/slab.c.
+ * This is useful if we need to approach a kernel structure obliquely,
+ * from its address obtained without the usual locking. We can lock
+ * the structure to stabilize it and check it's still at the given address,
+ * only if we can be sure that the memory has not been meanwhile reused
+ * for some other kind of object (which our subsystem's lock might corrupt).
+ *
+ * rcu_read_lock before reading the address, then rcu_read_unlock after
+ * taking the spinlock within the structure expected at that address.
  */
 #define SLAB_DESTROY_BY_RCU     0x00080000UL    /* Defer freeing slabs to RCU */
 #define SLAB_MEM_SPREAD         0x00100000UL    /* Spread some memory over cpuset */
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index cd401580bdd3..ca82e8ff89fa 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -41,8 +41,8 @@ struct kmem_cache {
 
         size_t colour;                  /* cache colouring range */
         unsigned int colour_off;        /* colour offset */
-        struct kmem_cache *slabp_cache;
-        unsigned int slab_size;
+        struct kmem_cache *freelist_cache;
+        unsigned int freelist_size;
 
         /* constructor func */
         void (*ctor)(void *obj);