Fixes to vma_migratable()

Remove check for VM_RESERVED: Now only used for statistical purposes.

Remove check for VM_DENYWRITE: Moving pages is not writing to them

Remove check for SHM pages: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
confirms that migrating SHM pages works.

Add a check for VM_HUGETLB. There is already a separate check for huge pages
in check_range() this is just in order to have a clean implementation.
A hugetlb vma cannot easily be migrated since the page sizes are different.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.15-rc5/mm/mempolicy.c
===================================================================
--- linux-2.6.15-rc5.orig/mm/mempolicy.c	2005-12-05 11:15:24.000000000 -0800
+++ linux-2.6.15-rc5/mm/mempolicy.c	2005-12-05 11:17:09.000000000 -0800
@@ -291,7 +291,7 @@ static inline int check_pgd_range(struct
 static inline int vma_migratable(struct vm_area_struct *vma)
 {
 	if (vma->vm_flags & (
-		VM_LOCKED|VM_IO|VM_RESERVED|VM_PFNMAP|VM_DENYWRITE|VM_SHM))
+		VM_LOCKED|VM_IO|VM_HUGETLB|VM_PFNMAP))
 		return 0;
 	return 1;
 }