Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux

Pull SLAB changes from Pekka Enberg:
 "The patches from Joonsoo Kim switch mm/slab.c to use 'struct page' for
  slab internals similar to mm/slub.c.  This reduces memory usage and
  improves performance:

    https://lkml.org/lkml/2013/10/16/155

  Rest of the changes are bug fixes from various people"

* 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux: (21 commits)
  mm, slub: fix the typo in mm/slub.c
  mm, slub: fix the typo in include/linux/slub_def.h
  slub: Handle NULL parameter in kmem_cache_flags
  slab: replace non-existing 'struct freelist *' with 'void *'
  slab: fix to calm down kmemleak warning
  slub: proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled
  slab: rename slab_bufctl to slab_freelist
  slab: remove useless statement for checking pfmemalloc
  slab: use struct page for slab management
  slab: replace free and inuse in struct slab with newly introduced active
  slab: remove SLAB_LIMIT
  slab: remove kmem_bufctl_t
  slab: change the management method of free objects of the slab
  slab: use __GFP_COMP flag for allocating slab pages
  slab: use well-defined macro, virt_to_slab()
  slab: overloading the RCU head over the LRU for RCU free
  slab: remove cachep in struct slab_rcu
  slab: remove nodeid in struct slab
  slab: remove colouroff in struct slab
  slab: change return type of kmem_getpages() to struct page
  ...

1 files changed, 8 insertions, 1 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 74f105847d13..c2bba248fa63 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -53,7 +53,14 @@
  *  }
  *  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 */