[PATCH] mm/slab: remove duplicate check

[Gavin Shan <shangw@linux.vnet.ibm.com>]

While allocateing pages using buddy allocator, the compound page
is probably split up to free pages. Under the circumstance, the
compound page should be destroied by function destroy_compound_page().
However, there has duplicate check to judge if the page is compound
one.

The patch removes the duplicate check since the function compound_order()
will returns 0 while the page hasn't PG_head set in function destroy_compound_page().
That's to say, the function destroy_compound_page() needn't check
PG_head any more through function PageHead().

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
---
 mm/page_alloc.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a712fb9..1277632 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -363,8 +363,7 @@ 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++;
 	}
-- 
1.7.5.4

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