Index: kernel/generic/include/mm/page.h
===================================================================
--- kernel/generic/include/mm/page.h	(revision 7c34822e63c6dd1cc781653743cea9cd94f08a18)
+++ kernel/generic/include/mm/page.h	(revision d0485c6a1e50e0398bb04d70d1e1ed89ea3db22a)
@@ -67,4 +67,10 @@
 #define PAGE_GLOBAL		(1<<PAGE_GLOBAL_SHIFT)
 
+
+/**
+ * Macro for computing page color.
+ */
+#define PAGE_COLOR(va)		(((va) >> PAGE_WIDTH) & ((1 << PAGE_COLOR_BITS) - 1))
+
 /** Page fault access type. */
 enum pf_access {
Index: kernel/generic/src/mm/as.c
===================================================================
--- kernel/generic/src/mm/as.c	(revision 7c34822e63c6dd1cc781653743cea9cd94f08a18)
+++ kernel/generic/src/mm/as.c	(revision d0485c6a1e50e0398bb04d70d1e1ed89ea3db22a)
@@ -551,10 +551,11 @@
  * @param dst_flags_mask Destination address space area flags mask.
  *
- * @return Zero on success or ENOENT if there is no such task or
- *	   if there is no such address space area,
- *	   EPERM if there was a problem in accepting the area or
- *	   ENOMEM if there was a problem in allocating destination
- *	   address space area. ENOTSUP is returned if an attempt
- *	   to share non-anonymous address space area is detected.
+ * @return Zero on success or ENOENT if there is no such task or if there is no
+ * such address space area, EPERM if there was a problem in accepting the area
+ * or ENOMEM if there was a problem in allocating destination address space
+ * area. ENOTSUP is returned if the address space area backend does not support
+ * sharing. It can be also returned if the architecture uses virtually indexed
+ * caches and the source and destination areas start at pages with different
+ * page colors.
  */
 int as_area_share(as_t *src_as, uintptr_t src_base, size_t acc_size,
@@ -581,4 +582,18 @@
 	}
 	
+#if 0	/* disable the check for now */
+#ifdef CONFIG_VIRT_IDX_CACHE
+	if (PAGE_COLOR(src_area->base) != PAGE_COLOR(dst_base)) {
+		/*
+		 * Refuse to create illegal address alias.
+		 */
+		mutex_unlock(&src_area->lock);
+		mutex_unlock(&src_as->lock);
+		interrupts_restore(ipl);
+		return ENOTSUP;
+	}
+#endif /* CONFIG_VIRT_IDX_CACHE */
+#endif
+
 	if (!src_area->backend || !src_area->backend->share) {
 		/*