mm/page_alloc: simplify page_is_buddy() for better code readability

Simplify page_is_buddy() to reduce the redundant code for better code
readability.
Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/1583853751-5525-1-git-send-email-qiwuchen55@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -792,32 +792,25 @@ static inline void set_page_order(struct page *page, unsigned int order)
  *
  * For recording page's order, we use page_private(page).
  */
-static inline int page_is_buddy(struct page *page, struct page *buddy,
+static inline bool page_is_buddy(struct page *page, struct page *buddy,
 							unsigned int order)
 {
-	if (page_is_guard(buddy) && page_order(buddy) == order) {
-		if (page_zone_id(page) != page_zone_id(buddy))
-			return 0;
-
-		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+	if (!page_is_guard(buddy) && !PageBuddy(buddy))
+		return false;
 
-		return 1;
-	}
+	if (page_order(buddy) != order)
+		return false;
 
-	if (PageBuddy(buddy) && page_order(buddy) == order) {
 	/*
-		 * zone check is done late to avoid uselessly
-		 * calculating zone/node ids for pages that could
-		 * never merge.
+	 * zone check is done late to avoid uselessly calculating
+	 * zone/node ids for pages that could never merge.
 	 */
 	if (page_zone_id(page) != page_zone_id(buddy))
-			return 0;
+		return false;
 
 	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
 
-		return 1;
-	}
-	return 0;
+	return true;
 }
 
 #ifdef CONFIG_COMPACTION