order-0 pages by definition cannot be compound so avoid the check in the
fast path for those pages.
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 59de90d5d3a3..5d205bcfe10d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1024,24 +1024,33 @@ void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
static bool free_pages_prepare(struct page *page, unsigned int order)
{
- bool compound = PageCompound(page);
- int i, bad = 0;
+ int bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
- VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
kasan_free_pages(page, order);
+ /*
+ * Check tail pages before head page information is cleared to
+ * avoid checking PageCompound for order-0 pages.
+ */
+ if (order) {
+ bool compound = PageCompound(page);
+ int i;
+
+ VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
+
+ for (i = 1; i < (1 << order); i++) {
+ if (compound)
+ bad += free_tail_pages_check(page, page + i);
+ bad += free_pages_check(page + i);
+ }
+ }
if (PageAnon(page))
page->mapping = NULL;
bad += free_pages_check(page);
- for (i = 1; i < (1 << order); i++) {
- if (compound)
- bad += free_tail_pages_check(page, page + i);
- bad += free_pages_check(page + i);
- }
if (bad)
return false;
--
2.6.4
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