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, 6 insertions, 13 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 31c512410a99..b90a74d28485 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -231,7 +231,6 @@ static void bad_page(struct page *page)
         printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
                 KERN_EMERG "Backtrace:\n");
         dump_stack();
-        page->flags &= ~PAGE_FLAGS_CLEAR_WHEN_BAD;
         set_page_count(page, 0);
         reset_page_mapcount(page);
         page->mapping = NULL;
@@ -468,16 +467,16 @@ static inline int free_pages_check(struct page *page)
                 (page_count(page) != 0)  |
                 (page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
                 bad_page(page);
-        if (PageDirty(page))
-                __ClearPageDirty(page);
-        if (PageSwapBacked(page))
-                __ClearPageSwapBacked(page);
         /*
          * For now, we report if PG_reserved was found set, but do not
          * clear it, and do not free the page.  But we shall soon need
          * to do more, for when the ZERO_PAGE count wraps negative.
          */
-        return PageReserved(page);
+        if (PageReserved(page))
+                return 1;
+        if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
+                page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+        return 0;
 }
 
 /*
@@ -621,13 +620,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
         if (PageReserved(page))
                 return 1;
 
-        page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_reclaim |
-                        1 << PG_referenced | 1 << PG_arch_1 |
-                        1 << PG_owner_priv_1 | 1 << PG_mappedtodisk
-#ifdef CONFIG_UNEVICTABLE_LRU
-                        | 1 << PG_mlocked
-#endif
-                        );
+        page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
         set_page_private(page, 0);
         set_page_refcounted(page);