mm: move page-flags include to top of file

Give up on the notion that we can remove page-flags.h from mm.h.  There
are currently 14 inline functions which use a PageFoo function.  Also, two
of the files directly included by mm.h include page-flags.h themselves,
and there are probably more indirect inclusions.  So just include it at
the top like any other header file.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200629151959.15779-3-willy@infradead.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -24,6 +24,7 @@
 #include <linux/resource.h>
 #include <linux/page_ext.h>
 #include <linux/err.h>
+#include <linux/page-flags.h>
 #include <linux/page_ref.h>
 #include <linux/memremap.h>
 #include <linux/overflow.h>
@@ -668,11 +669,6 @@ int vma_is_stack_for_current(struct vm_area_struct *vma);
 struct mmu_gather;
 struct inode;
 
-/*
- * FIXME: take this include out, include page-flags.h in
- * files which need it (119 of them)
- */
-#include <linux/page-flags.h>
 #include <linux/huge_mm.h>
 
 /*