diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 75fa100f542404f3b06b949e02dc3f79b1df548d..c56720136c45dddeef00730ec9306422720fce14 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2983,8 +2983,16 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
  * @caller:		  caller's return address
  *
  * Allocate enough pages to cover @size from the page level
- * allocator with @gfp_mask flags.  Map them into contiguous
- * kernel virtual space, using a pagetable protection of @prot.
+ * allocator with @gfp_mask flags. Please note that the full set of gfp
+ * flags are not supported. GFP_KERNEL would be a preferred allocation mode
+ * but GFP_NOFS and GFP_NOIO are supported as well. Zone modifiers are not
+ * supported. From the reclaim modifiers__GFP_DIRECT_RECLAIM is required (aka
+ * GFP_NOWAIT is not supported) and only __GFP_NOFAIL is supported (aka
+ * __GFP_NORETRY and __GFP_RETRY_MAYFAIL are not supported).
+ * __GFP_NOWARN can be used to suppress error messages about failures.
+ *
+ * Map them into contiguous kernel virtual space, using a pagetable
+ * protection of @prot.
  *
  * Return: the address of the area or %NULL on failure
  */