From: Andrew Morton <akpm@osdl.org>

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 mm/page-writeback.c |    4 ++++
 1 files changed, 4 insertions(+)

diff -puN mm/page-writeback.c~tracking-dirty-pages-in-shared-mappings-v4-fix2 mm/page-writeback.c
--- devel/mm/page-writeback.c~tracking-dirty-pages-in-shared-mappings-v4-fix2	2006-05-11 08:15:30.000000000 -0700
+++ devel-akpm/mm/page-writeback.c	2006-05-11 08:15:30.000000000 -0700
@@ -726,6 +726,10 @@ int test_clear_page_dirty(struct page *p
 						page_index(page),
 						PAGECACHE_TAG_DIRTY);
 			write_unlock_irqrestore(&mapping->tree_lock, flags);
+			/*
+			 * We can continue to use `mapping' here because the
+			 * page is locked, which pins the address_space
+			 */
 			if (mapping_cap_account_dirty(mapping)) {
 				page_wrprotect(page);
 				dec_page_state(nr_dirty);
_