On Tue, Aug 30, 2005 at 08:07:33PM +0100, Nicolas DET wrote:

By the way, I noticed that page_address() sometimes returns NULL when using
highmem (with a lot of mem).

You can only use page_address() on kernel-mapped memory.  For
non-GFP_KERNEL allocation you need to use kmap/kmap_atomic to map it
into kernel-virtual memory space.