1 files changed, 54 insertions, 57 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 74f105847d1..1e2f4fe1277 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 */
@@ -381,10 +388,55 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
 /**
  * kmalloc - allocate memory
  * @size: how many bytes of memory are required.
- * @flags: the type of memory to allocate (see kcalloc).
+ * @flags: the type of memory to allocate.
  *
  * kmalloc is the normal method of allocating memory
  * for objects smaller than page size in the kernel.
+ *
+ * The @flags argument may be one of:
+ *
+ * %GFP_USER - Allocate memory on behalf of user.  May sleep.
+ *
+ * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
+ *
+ * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
+ *   For example, use this inside interrupt handlers.
+ *
+ * %GFP_HIGHUSER - Allocate pages from high memory.
+ *
+ * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
+ *
+ * %GFP_NOFS - Do not make any fs calls while trying to get memory.
+ *
+ * %GFP_NOWAIT - Allocation will not sleep.
+ *
+ * %GFP_THISNODE - Allocate node-local memory only.
+ *
+ * %GFP_DMA - Allocation suitable for DMA.
+ *   Should only be used for kmalloc() caches. Otherwise, use a
+ *   slab created with SLAB_DMA.
+ *
+ * Also it is possible to set different flags by OR'ing
+ * in one or more of the following additional @flags:
+ *
+ * %__GFP_COLD - Request cache-cold pages instead of
+ *   trying to return cache-warm pages.
+ *
+ * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
+ *
+ * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
+ *   (think twice before using).
+ *
+ * %__GFP_NORETRY - If memory is not immediately available,
+ *   then give up at once.
+ *
+ * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
+ *
+ * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
+ *
+ * There are other flags available as well, but these are not intended
+ * for general use, and so are not documented here. For a full list of
+ * potential flags, always refer to linux/gfp.h.
  */
 static __always_inline void *kmalloc(size_t size, gfp_t flags)
 {
@@ -495,61 +547,6 @@ int cache_show(struct kmem_cache *s, struct seq_file *m);
 void print_slabinfo_header(struct seq_file *m);
 
 /**
- * kmalloc - allocate memory
- * @size: how many bytes of memory are required.
- * @flags: the type of memory to allocate.
- *
- * The @flags argument may be one of:
- *
- * %GFP_USER - Allocate memory on behalf of user.  May sleep.
- *
- * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
- *
- * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
- *   For example, use this inside interrupt handlers.
- *
- * %GFP_HIGHUSER - Allocate pages from high memory.
- *
- * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
- *
- * %GFP_NOFS - Do not make any fs calls while trying to get memory.
- *
- * %GFP_NOWAIT - Allocation will not sleep.
- *
- * %GFP_THISNODE - Allocate node-local memory only.
- *
- * %GFP_DMA - Allocation suitable for DMA.
- *   Should only be used for kmalloc() caches. Otherwise, use a
- *   slab created with SLAB_DMA.
- *
- * Also it is possible to set different flags by OR'ing
- * in one or more of the following additional @flags:
- *
- * %__GFP_COLD - Request cache-cold pages instead of
- *   trying to return cache-warm pages.
- *
- * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
- *
- * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
- *   (think twice before using).
- *
- * %__GFP_NORETRY - If memory is not immediately available,
- *   then give up at once.
- *
- * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
- *
- * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
- *
- * There are other flags available as well, but these are not intended
- * for general use, and so are not documented here. For a full list of
- * potential flags, always refer to linux/gfp.h.
- *
- * kmalloc is the normal method of allocating memory
- * in the kernel.
- */
-static __always_inline void *kmalloc(size_t size, gfp_t flags);
-
-/**
  * kmalloc_array - allocate memory for an array.
  * @n: number of elements.
  * @size: element size.