[PATCH] mm: cleanup the comment for head/tail pages of compound pages in mm/page_alloc.c

[Wang Sheng-Hui <shhuiw@gmail.com>]

Per the void prep_compound_page(struct page *page, unsigned long order) code,
compound pages use PG_head/PG_tail, and only tail pages point at head page
using their ->first_page field.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
---
 mm/page_alloc.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6e8ecb6..f645ce8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -332,8 +332,8 @@ out:
  *
  * The remaining PAGE_SIZE pages are called "tail pages".
  *
- * All pages have PG_compound set.  All pages have their ->private pointing at
- * the head page (even the head page has this).
+ * Head page has PG_head set, and all tail pages have PG_tail set. All tail
+ * pages have their ->first_page pointing at the head page.
  *
  * The first tail page's ->lru.next holds the address of the compound page's
  * put_page() function.  Its ->lru.prev holds the order of allocation.
-- 
1.7.1