From: Gavin Shan <shangw@linux.vnet.ibm.com>
Date: Tue, 14 Aug 2012 03:22:32 +0000 (+1000)
Subject: mm/slab: remove duplicate check
X-Git-Tag: next-20120905~3^2~41
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=945251454301478a984853c82636556cfa5b30e9;p=karo-tx-linux.git

mm/slab: remove duplicate check

While allocating pages using buddy allocator, the compound page is
probably split up to free pages.  Under these circumstances, the compound
page should be destroyed by destroy_compound_page().  However, there is a
duplicate check to judge if the page is compound.

Remove the duplicate check since the compound_order() returns 0 when the
page doesn't have PG_head set in destroy_compound_page().  That is to say,
destroy_compound_page() needn't check PageHead().

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c66fb875104a..5b3cc334b3bb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -368,8 +368,7 @@ static int destroy_compound_page(struct page *page, unsigned long order)
 	int nr_pages = 1 << order;
 	int bad = 0;
 
-	if (unlikely(compound_order(page) != order) ||
-	    unlikely(!PageHead(page))) {
+	if (unlikely(compound_order(page) != order)) {
 		bad_page(page);
 		bad++;
 	}