1 files changed, 12 insertions, 5 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index dca93fcb8b7a..4462b6a3fcb9 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -109,16 +109,23 @@ unsigned int kobjsize(const void *objp)
          * 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 || !virt_addr_valid(objp))
                 return 0;
 
+        page = virt_to_head_page(objp);
+
+        /*
+         * 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);
-
-        return (PAGE_SIZE << page->index);
+        /*
+         * The ksize() function is only guaranteed to work for pointers
+         * returned by kmalloc(). So handle arbitrary pointers here.
+         */
+        return PAGE_SIZE << compound_order(page);
 }
 
 /*