On Thu, 2011-03-31 at 15:16 +0200, Marek Szyprowski wrote:

+       ret = 0;
+       while (!PageBuddy(pfn_to_page(start & (~0UL << ret))))
+               if (WARN_ON(++ret >= MAX_ORDER))
+                       return -EINVAL; 

Holy cow, that's dense.  Is there really no more straightforward way to
do that?

In any case, please pull the ++ret bit out of the WARN_ON().  Some
people like to do:

#define WARN_ON(...) do{}while(0)

to save space on some systems.  

-- Dave