1 files changed, 26 insertions, 4 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index dca93fcb8b7a..3abd0845bda4 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;
 }
 
 /*