page-flags: define PG_reserved behavior on compound pages

As far as I can see there's no users of PG_reserved on compound pages.
Let's use PF_NO_COMPOUND here.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/page-flags.h

@@ -276,7 +276,8 @@ PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
 
-PAGEFLAG(Reserved, reserved, PF_ANY) __CLEARPAGEFLAG(Reserved, reserved, PF_ANY)
+PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
+	__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 PAGEFLAG(SwapBacked, swapbacked, PF_ANY)
 	__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_ANY)
 	__SETPAGEFLAG(SwapBacked, swapbacked, PF_ANY)

mm/hugetlb.c

@@ -1267,8 +1267,8 @@ static void prep_compound_gigantic_page(struct page *page, unsigned int order)
 
 	/* we rely on prep_new_huge_page to set the destructor */
 	set_compound_order(page, order);
-	__SetPageHead(page);
 	__ClearPageReserved(page);
+	__SetPageHead(page);
 	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
 		/*
 		 * For gigantic hugepages allocated through bootmem at