1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6fb2ae214152..a015236cc572 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -74,6 +74,21 @@ static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 #endif
 
 /*
+ * The largest kmalloc size supported by the slab allocators is
+ * 32 megabyte (2^25) or the maximum allocatable page order if that is
+ * less than 32 MB.
+ *
+ * WARNING: Its not easy to increase this value since the allocators have
+ * to do various tricks to work around compiler limitations in order to
+ * ensure proper constant folding.
+ */
+#define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT) <= 25 ? \
+                                (MAX_ORDER + PAGE_SHIFT) : 25)
+
+#define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
+#define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
+
+/*
  * Common kmalloc functions provided by all allocators
  */
 void *__kmalloc(size_t, gfp_t);