diff --git a/mm/nommu.c b/mm/nommu.c
index dca93fcb8b7a6517ad041221343bddf61e572644..3abd0845bda4a0901eed248ed96f7aef0c2f7ae8 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -104,21 +104,43 @@ EXPORT_SYMBOL(vmtruncate);
 unsigned int kobjsize(const void *objp)
 {
 	struct page *page;
+	int order = 0;
 
 	/*
 	 * If the object we have should not have ksize performed on it,
 	 * return size of 0
 	 */
-	if (!objp || (unsigned long)objp >= memory_end || !((page = virt_to_page(objp))))
+	if (!objp)
 		return 0;
 
+	if ((unsigned long)objp >= memory_end)
+		return 0;
+
+	page = virt_to_head_page(objp);
+	if (!page)
+		return 0;
+
+	/*
+	 * If the allocator sets PageSlab, we know the pointer came from
+	 * kmalloc().
+	 */
 	if (PageSlab(page))
 		return ksize(objp);
 
-	BUG_ON(page->index < 0);
-	BUG_ON(page->index >= MAX_ORDER);
+	/*
+	 * The ksize() function is only guaranteed to work for pointers
+	 * returned by kmalloc(). So handle arbitrary pointers, that we expect
+	 * always to be compound pages, here.
+	 */
+	if (PageCompound(page))
+		order = compound_order(page);
 
-	return (PAGE_SIZE << page->index);
+	/*
+	 * Finally, handle arbitrary pointers that don't set PageSlab.
+	 * Default to 0-order in the case when we're unable to ksize()
+	 * the object.
+	 */
+	return PAGE_SIZE << order;
 }
 
 /*