xen/balloon: Mark pages PG_offline in balloon_append()

Let's move the __SetPageOffline() call which all callers perform into
balloon_append().

In bp_state decrease_reservation(), pages are now marked PG_offline a
little later than before, however, this should not matter for XEN.
Suggested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

drivers/xen/balloon.c

@@ -158,6 +158,8 @@ static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 /* balloon_append: add the given page to the balloon. */
 static void balloon_append(struct page *page)
 {
+	__SetPageOffline(page);
+
 	/* Lowmem is re-populated first, so highmem pages go at list tail. */
 	if (PageHighMem(page)) {
 		list_add_tail(&page->lru, &ballooned_pages);
@@ -372,7 +374,6 @@ static void xen_online_page(struct page *page, unsigned int order)
 	for (i = 0; i < size; i++) {
 		p = pfn_to_page(start_pfn + i);
 		__online_page_set_limits(p);
-		__SetPageOffline(p);
 		balloon_append(p);
 	}
 	mutex_unlock(&balloon_mutex);
@@ -466,7 +467,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 			state = BP_EAGAIN;
 			break;
 		}
-		__SetPageOffline(page);
 		adjust_managed_page_count(page, -1);
 		xenmem_reservation_scrub_page(page);
 		list_add(&page->lru, &pages);
@@ -648,11 +648,9 @@ void free_xenballooned_pages(int nr_pages, struct page **pages)
 	mutex_lock(&balloon_mutex);
 
 	for (i = 0; i < nr_pages; i++) {
-		if (pages[i]) {
-			__SetPageOffline(pages[i]);
+		if (pages[i])
 			balloon_append(pages[i]);
 	}
-	}
 
 	balloon_stats.target_unpopulated -= nr_pages;
 
@@ -669,7 +667,6 @@ static void __init balloon_add_region(unsigned long start_pfn,
 				      unsigned long pages)
 {
 	unsigned long pfn, extra_pfn_end;
-	struct page *page;
 
 	/*
 	 * If the amount of usable memory has been limited (e.g., with
@@ -679,12 +676,10 @@ static void __init balloon_add_region(unsigned long start_pfn,
 	extra_pfn_end = min(max_pfn, start_pfn + pages);
 
 	for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
-		page = pfn_to_page(pfn);
 		/* totalram_pages and totalhigh_pages do not
 		   include the boot-time balloon extension, so
 		   don't subtract from it. */
-		__SetPageOffline(page);
-		balloon_append(page);
+		balloon_append(pfn_to_page(pfn));
 	}
 
 	balloon_stats.total_pages += extra_pfn_end - start_pfn;