fix sg_phys to use dma_addr_t

x86_32 CONFIG_HIGHMEM64G with 5GB RAM hung when booting, after issuing
some "request_module: runaway loop modprobe binfmt-0000" messages in
trying to exec /sbin/init.

The binprm buf doesn't see the right ".ELF" header because sg_phys()
is providing the wrong physical addresses for high pages: a 32-bit
unsigned long is too small in this case, we need to use dma_addr_t.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/linux/scatterlist.h

 #ifndef _LINUX_SCATTERLIST_H
 #define _LINUX_SCATTERLIST_H
 
+#include <asm/types.h>
 #include <asm/scatterlist.h>
 #include <linux/mm.h>
 #include <linux/string.h>
@@ -255,7 +256,7 @@ static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
  *   on the sg page.
  *
  **/
-static inline unsigned long sg_phys(struct scatterlist *sg)
+static inline dma_addr_t sg_phys(struct scatterlist *sg)
 {
 	return page_to_phys(sg_page(sg)) + sg->offset;
 }