mm/page_alloc.c: 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>
Acked-by: 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 5b74de6702e06587e0d4f36060f810526ff8fbe3..d1729472e5cdd6b7a86a39ed9cc9924955382c36 100644 (file)
--- 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++;
        }