remove mixture of non-atomic operations with page->flags which requires atomic operations to access

[William Lee Irwin III]

page->flags is effectively a lock word as its various bits are updatable
and accessible only by atomic operations. This patch removes the update
of page->flags in __free_pages_ok() with non-atomic operations in favor
of using atomic bit operations to update the bits to be cleared.

Against 2.5.19.

Cheers,
Bill

diff -Nru a/include/linux/page-flags.h b/include/linux/page-flags.h
--- a/include/linux/page-flags.h	Sun Jun  2 15:42:49 2002
+++ b/include/linux/page-flags.h	Sun Jun  2 15:42:49 2002
@@ -169,6 +169,7 @@
 
 #define PageChecked(page)	test_bit(PG_checked, &(page)->flags)
 #define SetPageChecked(page)	set_bit(PG_checked, &(page)->flags)
+#define ClearPageChecked(page)	clear_bit(PG_checked, &(page)->flags)
 
 #define PageReserved(page)	test_bit(PG_reserved, &(page)->flags)
 #define SetPageReserved(page)	set_bit(PG_reserved, &(page)->flags)
diff -Nru a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c	Sun Jun  2 15:42:49 2002
+++ b/mm/page_alloc.c	Sun Jun  2 15:42:49 2002
@@ -91,8 +91,12 @@
 	BUG_ON(PageLRU(page));
 	BUG_ON(PageActive(page));
 	BUG_ON(PageWriteback(page));
+
 	ClearPageDirty(page);
-	page->flags &= ~(1<<PG_referenced);
+	ClearPageUptodate(page);
+	ClearPageSlab(page);
+	ClearPageNosave(page);
+	ClearPageChecked(page);
 
 	if (current->flags & PF_FREE_PAGES)
 		goto local_freelist;