thp: add compound_trans_head() helper
Cleanup some code with common compound_trans_head helper.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/ksm.c b/mm/ksm.c
index 4d5a681..33781de 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -415,20 +415,11 @@
static struct page *page_trans_compound_anon(struct page *page)
{
if (PageTransCompound(page)) {
- struct page *head;
- head = compound_head(page);
+ struct page *head = compound_trans_head(page);
/*
- * head may be a dangling pointer.
- * __split_huge_page_refcount clears PageTail
- * before overwriting first_page, so if
- * PageTail is still there it means the head
- * pointer isn't dangling.
+ * head may actually be splitted and freed from under
+ * us but it's ok here.
*/
- if (head != page) {
- smp_rmb();
- if (!PageTransCompound(page))
- return NULL;
- }
if (PageAnon(head))
return head;
}