badpage: simplify page_alloc flag check+clear

Simplify the PAGE_FLAGS checking and clearing when freeing and allocating
a page: check the same flags as before when freeing, clear ALL the flags
(unless PageReserved) when freeing, check ALL flags off when allocating.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: 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, 8 insertions, 17 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 628ec0802492..219a523ecdb0 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -373,31 +373,22 @@ static inline void __ClearPageTail(struct page *page)
 #define __PG_MLOCKED            0
 #endif
 
-#define PAGE_FLAGS      (1 << PG_lru   | 1 << PG_private   | 1 << PG_locked | \
-                         1 << PG_buddy | 1 << PG_writeback | \
-                         1 << PG_slab  | 1 << PG_swapcache | 1 << PG_active | \
-                         __PG_UNEVICTABLE | __PG_MLOCKED)
-
-/*
- * Flags checked in bad_page().  Pages on the free list should not have
- * these flags set.  It they are, there is a problem.
- */
-#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | \
-                1 << PG_reclaim | 1 << PG_dirty | 1 << PG_swapbacked)
-
 /*
  * Flags checked when a page is freed.  Pages being freed should not have
  * these flags set.  It they are, there is a problem.
  */
-#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved)
+#define PAGE_FLAGS_CHECK_AT_FREE \
+        (1 << PG_lru   | 1 << PG_private   | 1 << PG_locked | \
+         1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
+         1 << PG_slab  | 1 << PG_swapcache | 1 << PG_active | \
+         __PG_UNEVICTABLE | __PG_MLOCKED)
 
 /*
  * Flags checked when a page is prepped for return by the page allocator.
- * Pages being prepped should not have these flags set.  It they are, there
- * is a problem.
+ * Pages being prepped should not have any flags set.  It they are set,
+ * there has been a kernel bug or struct page corruption.
  */
-#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \
-                1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked)
+#define PAGE_FLAGS_CHECK_AT_PREP        ((1 << NR_PAGEFLAGS) - 1)
 
 #endif /* !__GENERATING_BOUNDS_H */
 #endif  /* PAGE_FLAGS_H */