From: Andrea Arcangeli <andrea@suse.de>
Chris found that with data journaling a reiserfs pagecache may be truncate
while still pinned. The truncation removes the page->mapping, but the page
is still listed in the VM queues because it still has buffers. Then during
the journaling process, a buffer is marked dirty and that sets the PG_dirty
bitflag as well (in mark_buffer_dirty). After that the page is leaked
because it's both dirty and without a mapping.
So we must allow pages without mapping and dirty to reach the PagePrivate
check. The page->mapping will be checked again right after the PagePrivate
check.
Signed-off-by: Andrea Arcangeli <andrea@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/vmscan.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletion(-)
diff -puN mm/vmscan.c~orphaned-pagecache-memleak-fix mm/vmscan.c
--- 25/mm/vmscan.c~orphaned-pagecache-memleak-fix 2005-01-23 14:46:19.618336112 -0800
+++ 25-akpm/mm/vmscan.c 2005-01-23 14:46:19.622335504 -0800
@@ -306,8 +306,16 @@ static pageout_t pageout(struct page *pa
*/
if (!is_page_cache_freeable(page))
return PAGE_KEEP;
- if (!mapping)
+ if (!mapping) {
+ /*
+ * Some data journaling orphaned pages can have
+ * page->mapping == NULL while being dirty with clean buffers.
+ */
+ if (PageDirty(page) && PagePrivate(page) &&
+ try_to_free_buffers(page))
+ return PAGE_CLEAN;
return PAGE_KEEP;
+ }
if (mapping->a_ops->writepage == NULL)
return PAGE_ACTIVATE;
if (!may_write_to_queue(mapping->backing_dev_info))
_