thp: compound_lock

Add a new compound_lock() needed to serialize put_page against
__split_huge_page_refcount().

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 4805fdec8d6e..5a743cc87238 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -108,6 +108,9 @@ enum pageflags {
 #ifdef CONFIG_MEMORY_FAILURE
         PG_hwpoison,            /* hardware poisoned page. Don't touch */
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+        PG_compound_lock,
+#endif
         __NR_PAGEFLAGS,
 
         /* Filesystems */
@@ -397,6 +400,12 @@ static inline void __ClearPageTail(struct page *page)
 #define __PG_MLOCKED            0
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define __PG_COMPOUND_LOCK              (1 << PG_compound_lock)
+#else
+#define __PG_COMPOUND_LOCK              0
+#endif
+
 /*
  * Flags checked when a page is freed.  Pages being freed should not have
  * these flags set.  It they are, there is a problem.
@@ -406,7 +415,8 @@ static inline void __ClearPageTail(struct page *page)
          1 << PG_private | 1 << PG_private_2 | \
          1 << PG_buddy   | 1 << PG_writeback | 1 << PG_reserved | \
          1 << PG_slab    | 1 << PG_swapcache | 1 << PG_active | \
-         1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON)
+         1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
+         __PG_COMPOUND_LOCK)
 
 /*
  * Flags checked when a page is prepped for return by the page allocator.