diff --git a/[refs] b/[refs]
index eeea9a0d9168..39c65355d695 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3192b920bf7d0c528ab54e7d3689f44055316a37
+refs/heads/master: 90810645f78f894acfb04b3768e8a7d45f2b303a
diff --git a/trunk/include/linux/slab.h b/trunk/include/linux/slab.h
index 646a639a4aae..573c809c33d9 100644
--- a/trunk/include/linux/slab.h
+++ b/trunk/include/linux/slab.h
@@ -133,12 +133,22 @@ unsigned int kmem_cache_size(struct kmem_cache *);
 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_HIGH)
 #define KMALLOC_MAX_ORDER	(KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 
+/*
+ * Some archs want to perform DMA into kmalloc caches and need a guaranteed
+ * alignment larger than the alignment of a 64-bit integer.
+ * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
+ */
 #ifdef ARCH_DMA_MINALIGN
 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
 #else
 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
 #endif
 
+/*
+ * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
+ * Intended for arches that get misalignment faults even for 64 bit integer
+ * aligned buffers.
+ */
 #ifndef ARCH_SLAB_MINALIGN
 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
 #endif