mm/page_alloc.c: document bulkfree_pcp_prepare() return value

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: ke.wang <ke.wang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Zhaoyang Huang <huangzhaoyang@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

mm/page_alloc.c

@@ -1501,6 +1501,7 @@ static bool free_pcp_prepare(struct page *page, unsigned int order)
 	return free_pages_prepare(page, order, true, FPI_NONE);
 }
 
+/* return true if this page has an inappropriate state */
 static bool bulkfree_pcp_prepare(struct page *page)
 {
 	if (debug_pagealloc_enabled_static())